Selected category: Basic Science of Global Warming

How Do We Know That Humans Are Causing Climate Change? These Nine Lines of Evidence

While most Americans acknowledge that climate change is happening, some are still unsure about the causes.

They are often labeled “climate skeptics,” but that label can cause confusion or even anger.

Isn’t the nature of science to be skeptical? Isn’t it good to question everything?

Yes, but —

Here’s what is getting lost in the conversation:

Scientists have been asking these questions for nearly 200 years. The scientific community has been studying these questions for so long that collectively they have amassed an overwhelming amount of evidence pointing to a clear conclusion.

A similar situation is smoking and cancer. Nowadays, no one questions the link between smoking and cancer, because the science was settled in the 1960s after more than 50 years of research. The questions have been asked and answered with indisputable evidence.

We can think of the state of human activities and climate change as no different than smoking and cancer. In fact, we are statistically more confident that humans cause climate change than that smoking causes cancer.

Our confidence comes from the culmination of over a century of research by tens of thousands of scientists at hundreds of institutions in more than a hundred nations.

So what is the evidence?

The research falls into nine independently-studied but physically-related lines of evidence, that build to the overall clear conclusion that humans are the main cause of climate change:

  1. Simple chemistry that when we burn carbon-based materials, carbon dioxide (CO2) is emitted (research beginning in 1900s)
  2. Basic accounting of what we burn, and therefore how much CO2 we emit (data collection beginning in 1970s)
  3. Measuring CO2 in the atmosphere and trapped in ice to find that it is indeed increasing and that the levels are higher than anything we've seen in hundreds of thousands of years  (measurements beginning in 1950s)
  4. Chemical analysis of the atmospheric CO2 that reveals the increase is coming from burning fossil fuels (research beginning in 1950s)
  5. Basic physics that shows us that CO2 absorbs heat (research beginning in 1820s)
  6. Monitoring climate conditions to find that recent warming of the Earth is correlated to and follows rising CO2 emissions (research beginning in 1930s)
  7. Ruling out natural factors that can influence climate like the Sun and ocean cycles (research beginning in 1830s)
  8. Employing computer models to run experiments of natural vs. human-influenced “simulated Earths” (research beginning in 1960s)
  9. Consensus among scientists that consider all previous lines of evidence and make their own conclusions (polling beginning in 1990s)

(You can also see these nine lines of evidence illustrated in the graphic below)

Skeptics sometimes point to the last two supporting lines of evidence as weaknesses. They’re not. But even if you choose to doubt them, it is really the first seven that, combined, point to human activities as the only explanation of rising global temperatures since the Industrial Revolution, and the subsequent climate changes (such as ice melt and sea level rise) that have occurred due to this global warming.

The science is settled, and the sooner we accept this, the sooner we can work together towards addressing the problems caused by climate change – and towards a better future for us all.

 

(Click here for a pdf version of the graphic)

 

Also posted in Greenhouse Gas Emissions, Science, Setting the Facts Straight| 24 Responses

Climate Confusion in the Age of "Alternative Facts"

Earth as seen from a NOAA weather satellite. Photo: NASA

A very familiar type of ad recently appeared in the New York Times. It was the sort of fact-free manifesto normally found only on the fringes of the Internet, until someone with enough money decides to buy a full page in a newspaper.

These kinds of public declarations can be about anything from ancient nationalist grudges to fad nutritional theories. This one, by an obscure South Korean firm called Samsung Chemical Coating Company (no apparent relation to the electronics company), declared that carbon dioxide pollution isn’t causing climate change and that global warming will end in 2060 and be replaced by a destructive ice age, among other similarly oddball assertions.

Usually this kind of claim is barely worth refuting, as it is flatly contradicted by the consensus of the international scientific community. But one important detail made this ad different, and more dangerous.

First, let’s be clear about the substance of the ad and the real scientific facts.

There is absolutely no scientific basis or merit to the claims being made in the ad. No actual climate scientist takes seriously catastrophes in movies like The Day After Tomorrow becoming reality, or strange theories like the idea that creatures mutated from sunlight at the end of an ice age. No information about their “study” is available on the Internet, nor in the peer-reviewed scientific literature. There is no explanation about how they arrived at their conclusions, or any discussion of the information or data that served as the basis for their claims. And if you try Googling information about the authors, you’ll come up empty.

Even the more nuanced statements in the ad about the relationships between Earth’s precession, glacial cycles, and sea level rise are unsubstantiated. The authors use these unsupported claims as “proof” that carbon dioxide emissions do not cause global warming — an argument that should not be taken seriously given the lack of any supporting data. Their claims also demonstrate a profound ignorance of established physics. And the direct “certainty” throughout the ads about specific events – such as the disappearance of Earth’s magnetic field – adds to the characteristically unscientific approach.

All of these are hallmarks of the Crazy Full Page Ad.

Here is the truth:

  • The fact that carbon dioxide and other pollutants are changing our climate in dangerous ways has been established by decades of scientific research and mountains of data – from ice core samples, satellites, and other monitoring and analysis.
  • It is a conclusion strongly endorsed by the National Academies of Science, the scientists at NASA, the National Oceanographic and Atmospheric Association (NOAA), and all major American scientific organizations.
  • These climate pollutants, which have the known physical property of trapping heat, have been building up in our atmosphere since the world started burning lots of coal for the Industrial Revolution, and global average temperatures have risen right along with that accumulation.

So if all of this is nonsense, why protest so much?

Because at this moment in history, we have – amazingly, shockingly, dangerously – an Administrator of the Environmental Protection Agency (EPA) who makes similarly outlandish claims. In an appearance on CNBC last week, Scott Pruitt said:

I would not agree that [carbon dioxide] is a primary contributor to the global warming that we see.

In essence, he said he doesn’t know if the greatest environmental challenge of our time, his biggest responsibility, is real. It’s like having a surgeon general who doubts the connection between smoking and lung cancer. Or an attorney general who doesn’t consider the drug cartels to be dangerous organizations.

The result of Pruitt’s statements was a flood of outrage, reportedly locking up EPA’s switchboards like never before. (The agency had to set up an impromptu call center, according to leaks from employees.) Commentators on the left and right were stunned, even in an era when it’s a challenge to say something crazy enough to make the front page.

So what could normally be dismissed as a fringe ad cannot be ignored. We must, unfortunately, remind Americans who instinctively assume an EPA administration would know basic environmental science of the real facts. We must stand up and calmly explain what is at stake for our children and grandchildren. At EDF, we will continue to do that.

Also posted in Greenhouse Gas Emissions, News, Policy, Science| Comments are closed

Scott Pruitt Peddles Junk Science to Serve Trump’s Anti-Climate Agenda

This week has brought alarming indications that the Trump Administration is poised to roll back life-saving, common-sense climate protections with no plan for replacing them — and that the head of the U.S. Environmental Protection Agency (EPA) rejects basic facts about climate change and the clean air laws he is charged with carrying out.

These developments fundamentally threaten efforts to address climate change – the direst environmental challenge of our time.

News reports say that President Trump is on the verge of signing an executive order aimed at revoking the Clean Power Plan – the only national limits on climate-destabilizing carbon pollution from existing power plants, which are our nation’s largest source of these emissions.

EPA Administrator Scott Pruitt did an interview with CNBC in which he made the wildly inaccurate statement that there’s “tremendous disagreement” about the role climate pollution plays in climate change, and said that he does “not agree that [carbon dioxide] is a primary contributor to the global warming that we see.”

And in a second interview, on Fox Business, Pruitt questioned whether EPA has “the tools in the tool box to address [climate change],” and said “Congress has never spoken on this issue” — even though the Supreme Court has determined that the Clean Air Act, which was passed by Congress, does provide those “tools.”

Pruitt does not have a scientific background — just an extensive history of bringing highly politicized lawsuits against environmental protections, and of using his public office on behalf of the fossil fuel interests that have helped fund his political career.

His statements are not just false and misleading representations of climate science. They also call into question whether he can faithfully discharge his clear responsibility under our nation’s clean air laws to protect the public from climate pollution.

Pruitt Is Wrong on Climate Science

The U.S. government’s leading scientific agencies have conclusively determined that climate change is “due primarily to human activities” and is already manifesting itself in rising sea levels, heat waves, more intense storms, and other severe impacts felt by communities across the country.

Just in the last year, respected scientists have reported that the impact of human emissions on climate change is evident in February heat waves, devastating Louisiana storms, and flooded coastal communities.

Contrary to Pruitt’s statement that there’s “tremendous disagreement” about human impacts on climate, there is overwhelming scientific consensus that human emissions of carbon dioxide are destabilizing our climate. This consensus has been affirmed by many of our nation’s most respected scientists and scientific institutions, including:

NASA

Humans have increased atmospheric CO2 concentration by more than a third since the Industrial Revolution began. This is the most important long-lived ‘forcing’ of climate change. – NASA website

The planet’s average surface temperature has risen about 2.0 degrees Fahrenheit (1.1 degrees Celsius) since the late 19th century, a change driven largely by increased carbon dioxide and other human-made emissions into the atmosphere. – NASA press release

U.S. National Academy of Sciences

Direct measurements of CO2 in the atmosphere and in air trapped in ice show that atmospheric CO2 increased by about 40% from 1800 to 2012. Measurements of different forms of carbon … reveal that this increase is due to human activities. Other greenhouse gases (notably methane and nitrous oxide) are also increasing as a consequence of human activities. The observed global surface temperature rise since 1900 is consistent with detailed calculations of the impacts of the observed increase in atmospheric CO2 (and other human-induced changes) on Earth’s energy balance. – Climate Change: Evidence & Causes, page 5 (issued jointly with the Royal Society)

U.S. Global Change Research Program

Evidence from the top of the atmosphere to the depths of the oceans, collected by scientists and engineers from around the world, tells an unambiguous story: the planet is warming, and over the last half century, this warming has been driven primarily by human activity — predominantly the burning of fossil fuels. – U.S. Global Change Research Program website

More than 800 Earth Scientists (in a letter to then-President-Elect Donald Trump)

Publicly acknowledge that climate change is a real, human-caused, and urgent threat. If not, you will become the only government leader in the world to deny climate science. Your position will be at odds with virtually all climate scientists, most economists, military experts, fossil fuel companies and other business leaders, and the two-thirds of Americans worried about this issue. – scientists’ letter

Pruitt either refuses to accept this science, or is unaware of it – and either possibility presents a huge problem for the nation’s top environmental official.

Pruitt Has a Legal Obligation to Protect the Public from Climate Pollution

Pruitt’s assertions that “Congress has not spoken” on climate change and that EPA may lack the “tools” to address the issue show that he is just as wrong on the law as he is on climate science.

Our nation’s clean air laws require EPA to protect public health and well-being from all forms of dangerous pollution, and the Supreme Court has recognized on three separate occasions that this responsibility clearly applies to carbon dioxide and other climate-destabilizing pollutants. Contrary to Pruitt’s comments, the courts have consistently found that Congress has directly “spoken” to the issue of climate change by vesting EPA with broad responsibility and tools to address this and other emerging threats to human health and welfare.  And EPA has, in fact, put these tools into practice over the last few years by establishing common-sense protections that are reducing pollution, protecting public health, and strengthening our economy – including fuel efficiency and emission standards for cars and trucks, emission standards for power plants, and standards for oil and gas facilities.

In Massachusetts v. EPA, decided a decade ago, the Supreme Court found “without a doubt” that EPA is authorized to regulate carbon dioxide and other climate pollutants under the Clean Air Act:

Because greenhouse gases fit well within the Clean Air Act’s capacious definition of ‘air pollutant,’ we hold that EPA has the statutory authority to regulate the emission of such gases from new motor vehicles. — Massachusetts v. EPA, 2007

The Supreme Court then ordered EPA to make a science-based determination as to whether carbon dioxide and other climate pollutants endanger public health and welfare. In 2009 – after an exhaustive review of the scientific literature and over 380,000 public comments – EPA released its nearly 1,000-page finding that climate pollutants posed such a danger.

The U.S. Court of Appeals for the D.C. Circuit unanimously upheld this finding against a barrage of legal attacks by polluters and their allies (including a lawsuit by Scott Pruitt, who was then Attorney General of Oklahoma). The Supreme Court allowed that decision to stand without further review.

Two years after EPA made its determination, the Supreme Court unanimously decided in American Electric Power v. Connecticut that section 111(d) of the Clean Air Act – the provision that EPA relied upon in issuing the Clean Power Plan – clearly authorizes EPA to regulate emissions from existing power plants:

[Massachusetts v. EPA] made plain that emissions of carbon dioxide qualify as air pollution subject to regulation under the Act … And we think it equally plain that the [Clean Air] Act ‘speaks directly’ to emissions of carbon dioxide from the defendants’ plants. – American Electric Power v. Connecticut (2011)

And in Utility Air Regulatory Group v. EPA in 2014 the Supreme Court once again affirmed EPA’s responsibility to address climate pollution by finding that the Clean Air Act requires new and modified industrial facilities to adopt limits on climate pollution. Notably, at the oral arguments in both American Electric Power v. Connecticut and Utility Air Regulatory Group v. EPA, attorneys for some of the same coal-based power companies that now oppose the Clean Power Plan recognized EPA’s authority to regulate climate pollution from power plants.

As George W. Bush’s former EPA Administrator, Christine Todd Whitman, said in a recent interview:

I think, as a matter of law, that carbon is a pollutant has been settled. – (Climatewire, The Clean Power Plan is gone — and there's no 'replace' – March 9, 2017)

Notably, Scott Pruitt told the Senate under oath that he would abide by this framework. He specifically said that Massachusetts v. EPA and the Endangerment Finding are the “law of the land” and that “the endangerment finding is there and needs to be enforced and respected.” Pruitt ought to keep that testimony in mind should he try to attack the bedrock legal principles requiring EPA to protect the public from harmful climate pollution.

The Facts Are Clear

There is scientific consensus that human emissions of carbon dioxide and other climate pollutants are driving dangerous climate change. And under our nation’s clean air laws, EPA is required to protect Americans from this pollution – a responsibility that Pruitt’s predecessors have carried out by taking common-sense, cost-effective steps to reduce pollution from power plants, cars and trucks, oil and gas facilities, and other sources.

It’s outrageous and unacceptable that the principal federal official charged with carrying out this solemn responsibility is relying on “alternative facts” peddled by climate deniers to shirk his responsibility under the law.

 

Also posted in Clean Air Act, Clean Power Plan, Energy, Extreme Weather, Greenhouse Gas Emissions, News, Policy, Science, Setting the Facts Straight| Read 3 Responses

Scott Pruitt’s Misleading Senate Testimony – Will ‘Alternative Science’ Replace Real Science at EPA?

Earth as seen from a NOAA weather satellite. Photo: NOAA/NASA

As a climate scientist who is trained to base his conclusions strictly on scientific evidence and not politics, I find it particularly troubling that Scott Pruitt, President Trump’s pick to head the U.S. Environmental Protection Agency (EPA), is misrepresenting the scientific data that shows the earth’s atmosphere is warming.

Pruitt hopes to run the agency responsible for protecting the lives and health of Americans from environmental threats, and that includes reducing greenhouse gas emissions that are warming the planet. And as the Supreme Court has ruled, EPA has the authority to address greenhouse gases.

However, in his testimony before the Senate Environment and Public Works Committee on January 18, and then in follow-up written answers to Senators, Pruitt made several misleading, or flat-out inaccurate, statements.

In his attempt at subterfuge, Pruitt leaned on false and misleading climate-skeptic myths that have been debunked time and time again.

For instance, consider this one question and answer:

Written question from Sen. Jeff Merkley: Are you aware that each of the past three decades has been warmer than the one before, and warmer than all the previous decades since record keeping began in the 1880s? This trend is based on actual temperature measurements. Do you believe that there is uncertainty in this warming trend that has been directly measured? If so, please explain.

Written answer from Scott Pruitt: I am aware of a diverse range of conclusions regarding global temperatures, including that over the past two decades satellite data indicates there has been a leveling off of warming, which some scientists refer to as the "hiatus." I am also aware that the discrepancy between land-based temperature stations and satellite temperature stations can be attributed to expansive urbanization within in our country where artificial substances such as asphalt can interfere with the accuracy of land-based temperature stations and that the agencies charged with keeping the data do not accurately account for this type of interference. I am also aware that 'warmest year ever' claims from NASA and NOAA are based on minimal temperature differences that fall within the margin of error. Finally, I am aware that temperatures have been changing for millions of years that predate the relatively short modern record keeping efforts that began in 1880. (Questions for the Record, page 145)

In response to the scientific evidence that the last three decades have each been warmer than the one before it, Mr. Pruitt offered negligent claims that both the satellite data and surface based observations have shown there to be no warming over the last two decades – the so-called global warming hiatus.

Science does not agree with this assessment.

The idea of a hiatus and a potential discrepancy between satellite and surface based data have been under intense objective scrutiny by the scientific community for some time – and the results are in:

  • NOAA scientists recently published a peer reviewed article in the Journal Science that clearly shows the “hiatus” to have never existed.
  • Then last month a follow up study, undertaken by a separate group of researchers as an objective check on the NOAA result, also confirmed that the global warming hiatus never happened.
  • Additionally, the alleged satellite discrepancy has also been debunked – its origin an artifact of necessary, but potentially faulty, post-processing techniques that are employed when using data gathered by a satellite from space, as opposed to direct surface temperature measurements from thermometers. Stated plainly, raw satellite observations from space are not as accurate as those taken in the actual location, so these raw observations need to be quality controlled for scientific accuracy.

Next, in the same answer, in what can only be described as countering his own misguided narrative, Pruitt attempted to blame the increasing temperature trend – which he just stated did not exist via the hiatus argument – on an unfounded discrepancy between satellite based and urban land based data.He claimed the increase in urbanization was causing a fictitious rise in global temperature – an impact long shown to be minimal at best, especially when applied to the massive geographic expanse of the world relative to the lesser change in the geographic extent of cities.

Pruitt went on to quibble with the fact that 2016 was the warmest year ever recorded, by overemphasizing the role of negligible differences in how various scientific agencies around the world calculate the globally averaged temperature.

Actually, the diversity of approaches is a scientific strength, because it provides a balanced view of the data – much like seeking a second opinion on a medical diagnosis. It's vital to note that despite these trivial differences in methodology, the three long-running analyses by NASA, NOAA, and Great Britain’s UK Met Office all showed 2014 to 2016 to be the three consecutive warmest years on record. This fact is indisputable.

Pruitt concluded his misdirection by pointing out his awareness that temperatures have been changing for millions of years, and predating the relatively short modern record. Mr. Pruitt is indeed correct that the rapid warming in recent decades is quite alarming in the context of the much slower and longer term natural changes – although I don’t think that was what he was trying to say.

Pruitt seemed unaware of the latest scientific evidence on the various topics he chose to explore during his testimony. That indicates an ignorance of science coupled with a lack of preparation which adds up to being unfit to lead a scientifically-based government agency.

Also posted in Greenhouse Gas Emissions, News, Policy, Science, Setting the Facts Straight| Read 3 Responses

These Critical Disaster Safety Efforts Will Be at Risk if Trump Eliminates the Climate Action Plan

In 2012, Hurricane Sandy brought 14-feet storm surges to the unprotected New Jersey shore and billions in damages. Photo: State of New Jersey

As you’ve probably heard by now, President Trump has replaced the Obama administration’s Climate and Energy web page with a new one that reiterates our 45th president’s promise to tear down the Climate Action Plan and expand our reliance on fossil fuels.

What you may not know is that this 180-degree policy shift will also undermine efforts to prepare for climate change disasters that are already upon us – at a great cost to public safety and our nation’s economy.

By rescinding Obama’s plan for turning the corner on climate change – in which a main pillar was to prepare the United States for its impacts – President Trump would make it harder for:

  • businesses to manage extreme weather-related disruptions to their supply chains
  • infrastructure developers to account for changes in extreme weather and coastal flooding from sea level rise, and to be able to withstand climate surprises
  • farmers to become adept at managing continually changing precipitation patterns
  • states to manage their water resource operations more effectively
  • state and local emergency preparedness personnel to effectively manage safety risks

In 2016 alone, the hottest year on record, we experienced no fewer than 15 weather and climate change-related disasters – at a total cost of $46 billion in damages.

Storms and other such climate disasters with costs exceeding $1 billion have increased in the U.S. over the last 37 years.  These are hard dollar facts nobody can deny.

Economically responsible leaders today continue to build resilience in the face of a changing climate. Critical elements of our society – including businesses, infrastructure, agriculture, and essential water resources – depend on such action.

Keeping citizens safe

I watched President Trump express his condolences to the families who lost loved ones to the severe weather in the South in late January. But we can do more than just express empathy when American communities are torn apart by disasters.

We can also mitigate such disasters by improving our resilience to climate change and by advocating for climate-smart policies.

One of the most important ways to increase our preparedness for extreme climate events is to continually improve and refine our understanding of how climate variability and change is linked to extreme weather.

Obama’s Climate Action Plan aimed to do just that by helping federal climate science research break new ground and continue to advance our understanding of impacts from both short-term climate anomalies – such as how El Niño and La Niña affect severe weather – and from impacts related to warming caused by greenhouse gas emissions.

Throwing out the this plan is not how we protect the safety of our citizens, which, after all, should be the primary goal of any administration and the first way to keep America great.

Also posted in Extreme Weather, Policy, Science| Comments are closed

As Earth Gets Hotter, Scientists Break New Ground Linking Climate Change to Extreme Weather

So here we are again with yet another annual global temperature record. That’s right, 2016 will go down as the warmest year globally since record-keeping began, with preliminary reports indicating that 2016 was 1.3 degrees Celsius above pre-industrial times.

If it feels like you’ve heard this song before it’s because you have. The last three years have all smashed the previous year’s record for highest globally averaged temperature, a clear signal that the Earth continues its unprecedented rate of warming.

For sure, the 2016 record was helped along somewhat by one of the strongest El Niño events on record, but we also know that over many years, such cycles have very little to do with the overall global warming trend from rising greenhouse gas emissions. The trajectory is clear.

But there’s more to the story. As temperatures rise, we’re also learning more about how these rising temperatures affect our weather – and extreme weather events, in particular.

With the help of new and evolving climate research, we’re detecting a stronger link between warming and changing weather patterns.

Rapid response: Climate analysis in real time

Until recently, all studies on climate attribution were typically published a year or more after a big storm or heat wave, long after news headlines and public attention had waned.

But the science of climate attribution – an emerging and rapidly advancing branch of climate science that separates out the greenhouse gas cause from naturally occurring causes to quantify the human impact – is becoming nimble.

The World Weather Attribution project, an international effort “to sharpen and accelerate the scientific community’s ability to analyze and communicate the possible influence of climate change on extreme-weather events,” now conducts initial analyses in near real time.

In 2016, this project covered the March coral bleaching in the Pacific Ocean, the May European rain storms, the August Louisiana floods, the extreme Arctic warming during November and December, and the December cold air outbreak over the United States – all significant weather events.

In four of the five events, scientists found links to human-caused climate change, with the December cold air outbreak being the only event without a discernible human fingerprint.

The next step for climate science: to project how future weather events will change under different scenarios spelled out by the 2015 Paris climate agreement.

Extreme weather in a 1.5° or 2° degree world

Scientists are engaged in a new international research effort trying to predict differences in weather extremes under both a 1.5 degrees and 2 degrees Celsius warmer world, the targets discussed during the Paris climate talks.

Although climate change impacts on weather extremes are already underway, as 2016 has shown, it is critical to understand potential socioeconomic consequences under these two policy scenarios.

We’ve already experienced more than 1 degree Celsius of global warming and its impacts. The big question now is to what extent the next degree will be worse than the first.

As we continue to break heat records, quicker climate analyses and better predictions will be critical as we adjust to our rapidly changing climate – and science is on the case.

Also posted in Extreme Weather, News, Science| Comments are closed
  • About this blog

    Expert to expert commentary on the science, law and economics of climate change and clean air.

  • Get blog posts by email

    Subscribe via RSS

  • Categories

  • Meet The Bloggers