Wednesday, 23 August 2017

A Changing Climate

AJP

How will health services survive climate change impacts on rural and remote populations?


Climate change threatens to impact the lives of Australians living in rural and remote regions, through increased intensity of rainfall and tropical cyclones, high-fire danger days, drought and heat wave.
Scientists also predict agricultural viability will be compromised by drier soils and the unpredictability of extreme weather events, and exposure to air pollutants will increasingly impact population health, according to research published in the Australian Journal of Rural Health.
It is predicted that climate change effects will lead to increases in:
  • Physical injury;
  • Heat-related illness;
  • Nutritional disorders;
  • Infectious diseases;
  • Mental health issues;
  • Cardiorespiratory illnesses;
  • Skin cancer;
  • Food security;
  • Water security; and
  • Vector-borne diseases.
Medical practitioner researchers from the University of Notre Dame in Wagga Wagga, NSW, interviewed health service managers working in rural and remote areas, in order to determine their opinions of climate change impacts and strategies to strengthen the health service response.
There will be a need for pharmacists and other healthcare practitioners to adapt to climate change pressures.
The majority of respondents (90%) agreed that climate change would impact the health of rural populations in the future with regard to heat-related illnesses, mental health, skin cancer and water security.
And most participants identified the following population groups as being most vulnerable to the health impacts of climate change:
  • Farmers;
  • Homeless persons;
  • The elderly;
  • Children; and
  • Aboriginal and Torres Strait Islander People.
However many (72%) reported there is scepticism regarding climate change among both health professionals and community members – hampering their ability to strengthen health services in order to prepare for future climate challenges.
It was also discussed that there is a greater need for public health education about the impacts of climate change among staff and the community in local health districts.
“The role of health services in providing education about the health impacts of climage change is well recognised,” say authors Dr Rachel Purcell and Dr Joe McGirr.
“The need for health professionals to be aware of the health impacts of climate change has begun to be recognised in the policies and professional development activities of postgraduate training colleges and public health bodies.
“[Health service managers’] recommendations for strengthening the capacity of rural health services are integral to shaping the response of the rural health sector to climate change.”
There are several organisations including health practitioners with the collective goal of preparing for climate change and advocating for pro-environmental policies.
Most participants identified children and Aboriginal and Torres Strait Islander People as being some of the most vulnerable to the health impacts of climate change.
Pharmacists for the Environment Australia (PEA), for example, is involved in climate change advocacy and late last year became a member of Climate and Health Alliance.
The Climate and Health Alliance is a coalition of healthcare stakeholders who wish to see the threat to human health from climate change and ecological degradation addressed through prompt policy action.
As a member of the Climate and Health Alliance, Pharmacists for the Environment Australia says that it recognises “health care stakeholders have a particular responsibility to the community in advocating for public policy that will promote and protect human health.”
Doctors for the Environment Australia (DEA) is another active organisation that says one of their primary concerns is the health effects of climate change on humans and the biosphere on which humans depend.
“Global warming and climate change have serious implications for human health globally,” says the DEA in its May 2017 submission to the Federal Government’s discussion paper, Review of Australia’s Climate Change Policy.
“It is increasingly recognised that climate change is only one facet of a planetary health crisis; deforestation, air pollution, ocean acidification and biodiversity loss all pose grave threats to health,” they argue.
“Climate change threatens to further exacerbate problems in these domains. If the current trend continues, there is a real danger that efforts will be insufficient to prevent run-away global warming, which will have disastrous social, economic and health consequences.
“The mining and combustion of fossil-fuels, in particular coal, also have direct adverse effects from emission of toxic substances and pollution with particulates.
“The burden of repair of the environment is being passed to the next generations.”

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Climate Change Sets The World On Fire

Deutsche Welle

Southern Europe and British Columbia have been devastated by wildfires this summer. And they're not the only ones - it seems like much of the world is ablaze right now, and this could be the new normal.

There have been many wildfires aound the world this summer. Canada has seen the worst season for fires since records began, with 894,941 hectares burned, the British Columbia Wildfire Service has confirmed. Large areas of the Western United States have also been affected.
Meanwhile in Portugal, 2,000 people were recently cut off by flames and smoke encircling the town of Macao. And earlier this summer, 64 people were killed by a blaze in the country.
Like Canada, southern Europe has seen a record heatwave this year, creating hot, dry conditions that saw Italy, France, Croatia, Spain and Greece all swept by wildfires. As a result, Europe has reportedly seen three times the average number of wildfires this summer.
But it's not just Canada and southern Europe that have been affected. In Siberia, wildfire destroyed hundreds of homes, and around 700 hectares of Armenian forest have also been destroyed by fire. Earlier this year, Chile saw wildfires that were unparalleled in the country's history, according to the President.
Even Greenland, not known for its hot dry conditions, suffered an unprecedented blaze this summer.
Central Portugal has been one of the areas hardest hit by fires this summer
The big picture
"A lot of these things are happening locally, but people don't always connect them to climate change," said Kevin Trenberth, a scientist at the Climate Analysis Section of the National Center for Atmospheric Research in the US. "But there is a real climate change component to this and the risk is going up because of climate change."
With global temperatures rising, scientists say wildfires are likely to become increasingly frequent and widespread. "What's really happening is that there is extra heat available," Trenberth told DW. "That heat has to go somewhere and some of it goes into raising temperatures. But the first thing that happens is that it goes into drying - it dries out plants and increases the risk of wildfires."
The map above, compiling NASA satellite data on fires from the beginning of 2017 until mid-August makes it looks as if the whole world is on fire.
So is 2017 a record year of wildfires?
Wildfire rages in British Colombia, on July 8. It has now been confirmed the state's biggest in more than 50 years
Tough competition
It certainly looks like it's been a big year for fires in southern Europe and North America. But Martin Wooster, professor of earth observation science at King's College London, says other parts of the world have seen worse in recent years.
"For example, this year, fires across Southeast Asia are extremely unlikely to be anything like as severe as they were in 2015," he told DW.
Two years ago, drought caused by El Nino created lethal conditions for Indonesian forests and peatlands that were already degraded by draining and logging. The smoldering peat - ancient, decayed vegetable matter condensed into a carbon-heavy fuel - kept fires burning for months on end.
"This led to huge fires, far bigger than any seen in Europe, and some of the worst air pollution ever experienced," Wooster said.
NASA imagery shows a large wildfire burning in Sweden in early August
Longer fire seasons - longer recovery
But there does appear to be a distinct trend for fire seasons to be longer and more harsh. "In the western United States, the general perception is that there is no wildfire season any more, but that it's continuous all year round," Trenberth told DW.
In many parts of the world, wildfires are part of a natural cycle. Savannahs, for example, are maintained by fire. Some trees not only survive fires, but need them to release their seeds. Human intervention can disrupt these cycles, the scientific discipline of fire ecology has found. Putting out small fires can allow flammable debris to accumulate until a colossal fire starts that cannot be controlled.
But global warming is resulting in hotter, drier conditions that mean such infernos are becoming more common, even with careful forest management. And the changed climatic conditions can mean forests take far longer to recover. Meanwhile, fires are also starting in habitats in areas like the tropics that have no natural fire ecology.
A wildfire smolders near Nice in the south of France in July
Human fingerprints
Climate change isn't the only manmade factor. Fires can also be started by careless humans dropping cigarettes or letting campfires get out of control.
And in regions like the Amazon, where the annual fire season increased by 19 percent between 1979 and 2013, fire is deliberately used to clear forest to make way for agriculture. "Farmers light fires to clear an area and what happens in drought conditions is that these fires become wild because the vegetation is so dry, it gets out of control," Trenberth said.
And all this can have a feedback effect - more fires mean more carbon released into the atmosphere, which in turn drives climate change.
Wildfires rage through Southeast Europe: Too close for comfort
Smoke and flames rise from a fire in the Croatian village of Podstrana, near the Adriatic coastal town of Split, on July 18, 2017. In Croatia, the blazes have spread over several locations along the coast and onto the islands, engulfing pine forests and low shrubbery in extremely dry and windy weather.

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Dry Winter Primes Sydney Basin For Early Start Of Bushfire Season

The ConversationMatthias Boer | Rachael Helene Nolan | Ross Bradstock

Smoke from hazard reduction burning has blanketed parts of Sydney, as firefighters prepare for a ‘horrific’ bushfire season. AAP Image/Dean Lewins
It might feel like the depths of winter, but Australian fire services are preparing for an early start to the bushfire season. Sydney has been covered with smoke from hazard reduction burns, and the New South Wales Rural Fire Service has forecast a “horrific” season.
Predicting the severity of a bushfire season isn’t easy, and – much like the near-annual announcements of the “worst flu season on record” – repeated warnings can diminish their urgency.
However, new modelling that combines Bureau of Meteorology data with NASA satellite imaging has found that record-setting July warmth and low rainfall have created conditions very similar to 2013, when highly destructive bushfires burned across NSW and Victoria.
Crucially, this research has found we’re approaching a crucial dryness threshold, past which fires are historically far more dangerous.

How to measure bushfire fuel
On September 10, 2013 several bushfires in Sydney’s West caused havoc well before the official start of the bushfire season. These were a precursor to fires that destroyed more than 200 properties a month later. Warm, dry winter weather had dried out the fuels in Sydney’s forests and bush reserves beyond “normal” levels for the time of year.
The timing and severity of those preseason fires were a reminder that the region’s forests are flammable all year round; they can burn whenever the fuel they contain dries out past a certain threshold.
In most forests, there is an abundance of fuel in the form of leaf litter, dead twigs, branches and logs, lower vegetation such as shrubs and grasses, as well as higher foliage and branches.
The flammability of all these different kinds of fuel depends largely on their moisture content. Leaf litter and fine dead branches on the soil surface can dry out in a matter of days, whereas logs may take weeks or months to lose their moisture. The moisture content of shrubs and tree canopies varies depending on the amount of water in the soil, so they reflect the overall rainfall and temperatures across a whole season.
The flammability of an entire forest is therefore a complex calculation of all these different kinds of fuel (both alive and dead) and their different moisture levels.

Mapping Sydney’s forests
In a recent collaborative study, we combined data from a Bureau of Meteorology project that maps water availability levels across Australia with satellite imagery to develop new tools for mapping and monitoring moisture levels of different fuels in forests and woodlands.
We checked these tools by modelling fuel moisture levels during fires in NSW, Victoria and the ACT between 2000 and 2014, and comparing our predictions to historical bushfires.
Our research has identified critical dryness thresholds associated with significant increases in fire area. Rather than a gradual increase in flammability as forests dry out, when dead fuel moisture drops below 15% subsequent bushfires are larger. Another jump occurs when dead fuel moisture levels fall below 10%. We found similar thresholds in growing plants, although their moisture content is measured differently.
These dryness thresholds are pivotal, because they may represent the breakdown of moist natural barriers in landscapes that prevent fires from spreading. Understanding these mechanisms makes it possible to predict fire risk much more accurately.
As part of this project we compared the fuel moisture in Sydney Basin’s forested areas in 2013 and 2017. As shown in the chart below, currently the live fuel moisture level is tracking well below the 2013 values, and is approaching a crucial threshold (indicated by the dotted line).
The moisture content of dead fuel has been more variable, but it has also dipped below the 2013 curve and, if warm dry weather continues, could reach critical levels before the end of August.
The median predicted dead fuel moisture content and live fuel moisture content in forest areas of the Sydney Basin Bioregion in 2013 and 2017. Black dashed horizontal lines indicate fuel moisture threshold values. The start dates of major fires in 2013 are indicated by orange vertical lines. Author provided, Author provided
In another worrying sign, mapping shows critically dry live fuel is much more abundant in 2017 than it was in 2013.
Remotely sensed live fuel moisture content in forest areas of the Sydney Basin Bioregion in July 2013 (left) and July 2017 (right). Author provided
 It’s clear that much of the Sydney Basin is dangerously primed for major bushfires, at least until it receives major rainfall. Forecasts for windy but largely dry weather in coming weeks may exacerbate this problem.
These new insights into landscape-scale fuel dryness provide a powerful indicator of what might be expected. They also build our capacity for week by week monitoring of fire potential.
Preparation by both fire management authorities and exposed homeowners is now an immediate priority, to cope with the strong likelihood of an early and severe fire season.

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Tuesday, 22 August 2017

Australian Wind Delivers More Record Low Prices, As Private Sector Piles In

RenewEconomy - 

Just three months after Origin Energy stunned the renewables industry with a record low power off-take deal for the 530MW Stockyard Hill Wind Farm in Victoria, AGL Energy has delivered more of the same, securing an off-take price of below $60/MWh through the sale of its 453MW Coopers Gap Wind Farm, between Kingaroy and Dalby in Queensland’s south-east.
AGL said on Thursday it had reached financial close on the Sunshine State wind farm – which will be one of Australia’s biggest, once completed in 2019 – with the $22 million sale of the project to the Powering Australian Renewables Fund.
The deal includes AGL writing a PPA for electricity and associated renewable energy certificates of less than $60/MWh for an initial five years, with an option to extend the agreement for another five years at the same – or even lower – price.
AGL Macarthur Wind Farm. Source: AGL Blog
In a media statement, AGL said it expected the project to cost a total of around $850 million, funded through a combination of PARF partners’ equity and a lending group including Westpac, Sumitomo Mitsui Banking Corporation, Mitsubishi UFJ Financial Group, Societe Generale, DBS Bank, Mizuho Bank and ABN Amro.
The result is undoubtedly a good one for AGL, which created PARF just one year ago, in partnership with the Queensland Investment Corporation, with the goal of using it to underwrite 1,000MW of large-scale renewables to be operated and managed by AGL.
After making its first acquisition in November 2016, buying up the 102MW Nyngan and 52MW Broken Hills solar farms as seed assets, it has managed to keep growing its portfolio, adding the 200MW Silverton NSW wind farm in January 2017.
“More than 800 MW of projects have now been vended into PARF in its first 12 months of operation,” said AGL CEO Andy Vesey in comments on Thursday.
“The strong support we have received from our equity partners and lenders for these projects is testament to the readiness of the private sector to invest in Australia’s energy transformation.”
But Vesey – who recently attended a meeting of energy retail chiefs in Canberra to discuss the problem of Australia’s world-topping electricity prices – was keen to stress that public policy settings remained vital to maintain investor momentum.
“Certainty on energy policy, including the implementation of the recommendations of the Finkel Review, will enable more projects of this kind to go ahead and help place downward pressure on energy prices by increasing supply,” he said.
AGL COO Brett Redman said the Coopers Gap deal has demonstrated the effectiveness of the investment model, the falling price and increasing efficiency of renewables technology and the key role it had to play in Australia’s future energy market.
The project, which will be developed by GE and Catcon, will use 123 specially designed GE turbines to produce around 1,510,000MWh of energy annually – enough to power more than 260,000 average Australian homes.
For GE, the Coopers Gap contract will bring the global giant’s total installed wind capacity to almost 1.4GW in Australia by 2019, when the wind farm is expected to be completed. It is GE’s first wind project in Queensland.
“That’s the largest number of megawatts in a single year by any GE onshore wind country outside the United States, ever,” said Pete McCabe, GE’s global president and CEO of GE Renewable Energy’s Onshore Wind business.

McCabe, too, took the opportunity of this week’s news to call for strong and stable renewable energy policy in Australia.
“Australia is a great market for wind, and today is GE’s second largest region globally for our Renewables business. While we see lots of opportunities in Australia, we need to continue to have policy certainty to drive investment.”
GE said the successful formula for its bid for Cooper’s Gap included custom-designed 115-metre towers for the 3.8MW turbines, to get the optimal wind speed.
The engineering team – which included German wind engineering “boffin” Dr Joerg Winterfeldt – had to ensure that the design of the taller tower avoided vibration when the blades turn and also fit within the logistical puzzle of not being too heavy or wide to cross all the roads and bridges from port to site.

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The Trump Administration Just Disbanded A Federal Advisory Committee On Climate Change

Washington PostJuliet Eilperin

President Trump speaks about the U.S. role in the Paris climate change accord in the Rose Garden of the White House in June. (AP)
The Trump administration has decided to disband the federal advisory panel for the National Climate Assessment, a group aimed at helping policymakers and private-sector officials incorporate the government’s climate analysis into long-term planning.
The charter for the 15-person Advisory Committee for the Sustained National Climate Assessment — which includes academics as well as local officials and corporate representatives — expires Sunday. On Friday, the National Oceanic and Atmospheric Administration’s acting administrator, Ben Friedman, informed the committee’s chair that the agency would not renew the panel.
The National Climate Assessment is supposed to be issued every four years but has come out only three times since passage of the 1990 law calling for such analysis. The next one, due for release in 2018, already has become a contentious issue for the Trump administration.
Administration officials are currently reviewing a scientific report that is key to the final document. Known as the Climate Science Special Report, it was produced by scientists from 13 different federal agencies and estimates that human activities were responsible for an increase in global temperatures of 1.1 to 1.3 degrees Fahrenheit from 1951 to 2010.
The committee was established to help translate findings from the National Climate Assessment into concrete guidance for both public and private-sector officials. Its members have been writing a report to inform federal officials on the data sets and approaches that would best be included, and chair Richard Moss said in an interview Saturday that ending the group’s work was shortsighted.
“It doesn’t seem to be the best course of action,” said Moss, an adjunct professor in the University of Maryland’s Department of Geographical Sciences, and he warned of consequences for the decisions that state and local authorities must make on a range of issues from building road projects to maintaining adequate hydropower supplies. “We’re going to be running huge risks here and possibly end up hurting the next generation’s economic prospects.”
But NOAA communications director Julie Roberts said in an email Saturday that “this action does not impact the completion of the Fourth National Climate Assessment, which remains a key priority.”
While many state and local officials have pressed the federal government for more concrete guidance on how to factor climate change into future infrastructure, President Trump has moved in the opposite direction. Last week, the president signed an executive order on infrastructure that included language overturning a federal requirement that projects built in coastal floodplains and receiving federal aid take projected sea-level rise into account.
Seattle Mayor Ed Murray (D) said in an interview Saturday that the move to dissolve the committee represents “an example of the president not leading, and the president stepping away from reality.” An official from Seattle Public Utilities has been serving on the panel; with its disbanding, Murray said it would now be “more difficult” for cities to participate in the climate assessment. On climate change, Trump “has left us all individually to figure it out.”
Richard Wright, the past chair of the American Society of Civil Engineers’ Committee on Adaptation to a Changing Climate, has been working with the committee to convey the importance of detailed climate projections in next year’s assessment. The society establishes guidelines that form the basis of building codes across the country, and these are based on a historical record that may no longer be an accurate predictor of future weather extremes.
“We need to work on updating our standards with good estimates on what future weather and climate extremes will be,” Wright said Saturday. “I think it’s going to be a serious handicap for us that the advisory committee is not functional.”
The committee was established in 2015, but its members were not appointed until last summer. They convened their first meeting in the fall. Moss said members of the group intend to keep working on their report, which is due out next spring, even though it now will lack the official imprimatur of the federal government. “It won’t have the same weight as if we were issuing it as a federal advisory committee,” he said.
Other Trump Cabinet officials have either altered the makeup of outside advisory boards or suspended these panels in recent months, though they have not abolished the groups outright. Environmental Protection Agency Administrator Scott Pruitt decided to replace dozens of members on one of the agency’s key scientific review boards, while Interior Secretary Ryan Zinke is “reviewing the charter and charge” of more than 200 advisory boards for his department.

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Coral Bleaching: Researchers Struggle To Find Anywhere In Pacific Ocean Untouched

ABC News - Nadia Daly

The vessel Tara is studying how coral reefs in the Pacific are adapting to climate change. (Supplied: Tara expedition)
Scientists aboard a French research ship say they have been shocked to see the extent of coral bleaching across the Pacific Ocean, just halfway through their two-year voyage around the world.
The vessel Tara has been sailing around the globe for more than a decade to study the effects of climate change on the ocean.
Its current expedition will cross 11 time zones and span 100,000 kilometres from Europe to Asia and back again, and the group claims it is the biggest study of this scale across coral reefs.
The focus is how coral reefs in the Pacific are adapting to climate change, and on a stopover in Sydney, captain Nicolas De La Brosse said the extent of damage is already deeply troubling.
Captain Nicolas De La Brosse said there was even coral bleaching in areas far from heavy pollution. (ABC News: Nadia Daly)
"What we've seen in really isolated spots like Samoa for example, even though it's very far away from [developed] countries with pollution, we struggled to find any coral life," he said.
Mr De La Brosse said nowhere was immune to the effects of global warming.
"It doesn't matter where you are in the Pacific, coral is starting to bleach."
He said data was still being collected and analysed and the final results would be released at the end of 2019.
The ship is not just a floating science lab — it is a temporary home for 16 people, including engineers, scientists, sailors, crew and, of course, a cook who whips up French dishes and sometimes, local favourites.
"When we arrived in Australia I made a banana cake because I know in Australia you have this cake," chef Dominique Limbour said.
Spending months at a time at sea together in the 26-metre vessel can be a challenge.
"We have to work all together. You can't argue with someone else — you have to be pretty easygoing," Mr De La Brosse said.
After its Sydney stop the ship will head north to study the extent to which coral in the Great Barrier Reef is adapting to climate change.
The vessel, which has been sailing around the globe for more than a decade, docked at Darling Harbour. (ABC News: Nadia Daly)
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Monday, 21 August 2017

What Should You Say To A Climate Change Skeptic?

Los Angeles Times - Mira Abed

Greenhouse gases are released from a factory in Australia. (Dave Hunt / European Pressphoto Agency)
We’ve all been there: The perfectly innocuous conversation you’ve been having at a friend’s party or your kid’s soccer game devolves into an argument about climate change. Suddenly, you realize you’re talking to a climate change skeptic.
You want to help your acquaintances see the light. But how?
We asked climate scientists and communicators how to have constructive discussions about climate change. They offered both general advice about how to engage and specific information to rebut doubters’ claims.
Start by looking for common ground. We all depend on the same planet for our survival, and all of us want a good outcome, said Richard Alley, a geoscientist at Penn State University who studies abrupt changes in the climate.
Also, recognize that there’s a grain of truth in most of the arguments put out by climate skeptics — or at least an intriguing question that climate scientists have considered at some point. Acknowledging the merits of these ideas often leads to more productive discussions, said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies in New York.
Read on and you’ll be ready when the next unexpected debate comes your way.

Beware of cherry-picking
In many cases, so-called evidence against climate change is drawn from a zoomed-in picture, like data taken from a short time period or a single geographical location. It’s not that the information is wrong — it may just be taken out of context.
Climate scientists emphasize the need to look at global data over long periods to understand it in context and see larger trends. For example, it’s easy to pick an exceptionally hot year — like 1998 — and point out that the average global temperature was only 0.1° Celsius warmer than in 2008, a relatively cool one. But all this example shows is that there are fluctuations from year to year.
Atmospheric carbon dioxide has risen exponentially in the last century. (NASA)
What really matters, climate scientists say, is that the global average temperature is on a rising trend. NOAA’s 2016 climate report shows that every year since 1977 has been warmer than the 20th century average. This means the Earth is retaining more heat over time.
Always ask skeptics about the data their argument is based on. If it’s from an isolated location or a small chunk of time, it may not be representative of the bigger picture.

Greenhouse gases are the key
When looking for something to blame for rising temperatures, skeptics tend to focus on natural factors that can shift over time, such as the intensity of the sun, the amount of volcanic activity or changes in Earth’s orbit. They may even acknowledge the role of certain man-made pollutants like ozone or aerosols.
But all of these factors are dwarfed by the impact of greenhouse gases.
When we burn fossil fuels in cars, planes and power plants, the hydrocarbon molecules in the fuel break down to produce carbon dioxide and water. Both are then released into the atmosphere.
Emissions spew from a large stack at a coal-fired power plant in Newburg, Md. (Mark Wilson / Getty Images)
Carbon dioxide (CO2) and some other small molecules, such as methane (CH4) and nitrous oxides (NOx), are known as greenhouse gases because they absorb and trap light from the sun as well as infrared radiation coming from the Earth’s surface. Both are converted into heat by these gases that warms the air — much like a greenhouse does.
Carbon dioxide is the most important greenhouse gas by far, Alley said. Every time the climate has changed in ways that scientists can measure, carbon dioxide has had something to do with it, he said.
The NASA Goddard Institute for Space Studies in New York modeled the impact of a variety of natural and industrial factors on global temperature. They found that only carbon dioxide levels predicted the temperature increase we’ve seen in recent decades. This visualization from Bloomberg makes it easy to see.
Methane and nitrous oxides actually have more powerful greenhouse effects than carbon dioxide — but carbon dioxide has a larger overall influence because we’re releasing so much more of it. According to the Environmental Protection Agency, carbon dioxide accounted for 82% of all greenhouse gas emissions in 2015.

Humans are responsible for the surge in carbon dioxide
Where did all that carbon dioxide come from? When looking at the concentrations of CO2 over time, “nothing interesting happened until we started burning coal,” Schmidt said.
That’s when atmospheric CO2 really picked up — and it’s increased exponentially ever since.
According to data compiled by the Goddard Institute, carbon dioxide was at an atmospheric concentration of 291 parts per million in 1880. It had risen to 311 ppm by 1950 and to 370 ppm by 2000. NOAA’s reported global annual average reached 402 ppm in 2016.


Carbon dioxide concentration changes throughout the year. Shown here: September 2014 - August 2015 (NASA)

Climate change skeptics often point out that volcanic eruptions and decaying plants also send carbon dioxide into the atmosphere. But multiple studies have shown that human activity produces at least 60 times more carbon dioxide than volcanoes do each year. And while it’s true that plants produce more carbon dioxide than humans, they clean up after themselves — and even pick up some of our slack.
This is one reason the concentration of carbon dioxide in the atmosphere is higher in the winter than in the summer. Plants come with their own carbon sinks – they produce carbon dioxide when they die and decay, but new plants also absorb it from the air as they grow.

You can’t blame warming on the sun
Climate change deniers say the sun is the obvious source of the planet’s heat. After all, it’s constantly bathing us in 173,000 terawatts of energy. That’s about 10,000 times more than enough to meet the entire world’s annual energy needs.
But solar activity has actually decreased since 1950, experts said. This means that if nothing else had changed, we would be experiencing a cooling cycle right now.
Solar energy output varies slightly over an 11-year cycle, and that does have an effect on temperature. But these effects are much clearer in the stratosphere than in the lower atmosphere, Schmidt said, and the solar cycle doesn’t significantly affect surface temperatures on Earth.
A Salvation Army hydration station sign sits in the midday sun as the temperature climbs to a near-record high in Phoenix. (Ross D. Franklin / Associated Press)
 Typically, solar activity and temperature move together: When one rises, the other does too. So when we see solar activity and temperature moving in opposite directions, as has happened recently, we know that something else is going on.
Other factors are also encouraging cooling right now, several experts said, including an increase in reflective aerosols like sulfates and nitrates in the atmosphere. These block some heat from reaching the Earth’s surface.
If not for these cooling influences, our planet would be warming even more rapidly.

This is not a normal part of a natural cycle
Climate change has occurred naturally in the past. But that doesn’t mean natural causes are responsible this time.
Alley pointed out the logical flaw in this oft-repeated argument: It’s like saying that since wildfires sometimes begin with natural events like lightning strikes they can never be caused by a wayward campfire.
The climate doesn’t change unless it’s forced to change. And during the 20th century, there weren’t any natural events powerful enough to account for the changes scientists are documenting.
“Human fingerprints are all over this,” said John Cook, a cognitive scientist who studies beliefs about climate change at George Mason University.
And just because the climate has changed before doesn’t mean we want it to happen again — especially this quickly. In the past, rapid changes were usually pretty hard on living creatures that didn’t have enough time to adapt to their new conditions. That doesn’t bode well for us.

Don’t be fooled by Antarctic sea ice
For a several years in the early part of the decade, the amount of sea ice extending from Antarctica set new records, peaking at 7.72 million square miles (an area more than twice as large as the United States).
Climate change skeptics say this is inconsistent with a warming planet. But they ignore the fact that the vast majority of sea ice is decreasing. (Remember the warning about cherry-picking?) Even in Antarctica, it has been losing ground rapidly since 2014 and has now sunk to a record low.
Arctic sea ice hasn’t varied as widely in recent years. According to a report released in 2014 by the U.S. National Academy of Sciences and the Royal Society in London, the yearly minimum Arctic sea ice extent in the summer has decreased by 40% since 1978. This could be the least icy the Arctic has been in almost 1,500 years, the report noted. Some researchers say that Arctic summers could be completely ice-free by 2030.
Finnish icebreaker MSV Nordica passes through Victoria Strait while transiting the Northwest Passage connecting the Pacific and Atlantic oceans earlier than had ever been recorded. (David Goldman / Associated Press)
Richard Somerville, a climate scientist who spent many years at the Scripps Institute of Oceanography, points out that sea ice is highly variable.
“It’s not simple — the ice doesn’t just melt when the temperature falls below 32° Fahrenheit,” he said. “It gets blown around by the winds and carried around by the currents, and it gets blown or carried to regions that are either more prone to melting or less prone to melting.”
He likens sea ice trends to the stock market: Although it fluctuates from year to year, the overall trend can be seen when we look at long time periods — and now it’s a downward one. Focusing on short-term changes misses this bigger truth, he said.
The take-home message is that sea ice is complicated, so be careful not to jump to conclusions — in either direction. For example, the collapse of an iceberg that broke off from Antarctica in July has not been definitively tied to climate change.

Recognize that this is a political debate, not a scientific one
Skeptics like to say that scientists don’t agree on climate change, but the truth is that the consensus is overwhelming.
A whopping 97% of climate scientists share the view that climate change is happening now and that human activity is to blame.
Greenpeace activists in Spain protest President Trump's decision to withdraw from the Paris climate accord. (Mariscal / European Pressphoto Agency)
It’s important to understand where science ends and politics begins. To boost your chances for success, make a point of separating the two, Somerville said. Many people are not suspicious of the science, but rather of the consequences associated with climate change.
“There’s no such thing as a Democratic or Republican thermometer,” Somerville said. We can agree on what the science says, even if we have different political ideas, he added.

Understand why people may be misinformed
According to a recent poll conducted by researchers at Yale and George Mason University, only half of the American public realizes that a majority of climate scientists agree on climate change. Only 13% of those polled were aware that the degree of scientific consensus is upwards of 90%.
A number of factors have led to this widespread misunderstanding, Cook said.
First, some industry groups who oppose environmental regulation have made a concerted effort to confuse the public about climate change.
Additionally, media reports tend to include two sides to every story, including those about climate change. But that implies that both sides have equal weight, even when they don’t.
Finally, the sheer volume of climate change information is daunting, and many Americans don’t have the time or energy to sort fact from fiction. “Because there’s so much noise, people tend to disengage,” Cook said.

And finally, know when to cut your losses
As with any contentious issue, you have to realize when you’re talking to someone who just wants to argue.
“If that’s the case, just stop.” Schmidt said.

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