Climate Climate & Energy

Here’s why the scientific community thinks so

This is a "greatest hit" from my previous blog. It's a topic that comes up all the time, so I think it's worth a reprise.

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As George Bush said at a recent press conference: "the globe is warming. The fundamental debate: Is it manmade or natural?"

Why does the scientific community think humans are significantly contributing to today's warming?

To understand why, first recognize that whenever the climate shifts, there's a reason for it. It does not wander around like a drunken sailor.

Based on decades of research, we can identify the factors that have influenced climate in the past:

‘Position statements hide debate’–True enough, but that is not the whole picture

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: All those institutional position statements are fine, but by their very nature they paper over debate and obscure the variety of individual positions. The real debate is in the scientific journals.

Answer: This is a fair point. Group position statements are designed to present a united front. The best indicator of what individual scientists think is in the current scientific literature, where new and different is the paramount value and scientists are free to express their own ideas, as long as they're supported by data and logic. What does the literature look like in terms of the climate debate? Sounds like a good topic for research.

Herd It Through the Decline

Climate change ravages land and livelihoods of Kenya’s nomadic herders As climate talks continue in Nairobi, Kenya, the world’s climate-change canaries aren’t far away. Severe floods in the country’s northern and coastal regions have killed more than 20 people and forced 60,000 to relocate over the last few weeks, and a flood-drought cycle is disrupting […]

‘There is no consensus’–If this is not consensus, what would consensus look like?

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: Climate is complicated and there are lots of competing theories and unsolved mysteries. Until this is all worked out, one can't claim there is consensus on global warming theory. Until there is, we should not take any action.

This is similar to the "global warming is a hoax" article, but at least here we can narrow down just what the consensus is about.

Answer: Sure there are plenty of unsolved problems and active debates in climate science. But if you look at the research papers coming out these days, the debates are about things like why model predictions of outgoing longwave radiation at the top of the atmosphere in tropical latitudes differ from satellite readings, or how the size of ice crystals in cirrus clouds affect the amount of incoming shortwave reflected back into space, or precisely how much stratospheric cooling can be attributed to ozone depletion rather than an enhanced greenhouse effect.

No one in the climate science community is debating whether or not changes in atmospheric CO2 concentrations alter the greenhouse effect, or if the current warming trend is outside of the range of natural variability, or if sea levels have risen over the last century.

This is where there is a consensus.

If global warming is an emergency, then let’s act like it

On a recent Monday morning, at exactly 8 a.m., a dozen global-warming activists converged in Washington, D.C., at the main entrance to the National Oceanic and Atmospheric Administration. Will a D.C. protest get the ball rolling? Photo: climateemergency.org Two activists dressed as window washers — painter’s hats on, squeegees in hand — carried a 32-foot […]

Direct-action protesters in the U.K. are focusing on climate change

A protester at England’s Didcot power station contemplates the changing landscape. Photo: Kate Davison/Greenpeace It’s half an hour or so after the end of Britain’s biggest-ever protest against climate change, and I’m still hanging out in Trafalgar Square. A few groups of kids are milling around, and a couple of anarchists have set up a […]

‘Global warming is a hoax’–I wish James Inhofe were just a hoax …

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: Global warming is a hoax perpetrated by environmental extremists and liberals who want an excuse for more big government (and/or world government via the U.N.).

This is a common line, regardless of how ridiculous it is, so it should not go unanswered.

Answer: Here is a list of organizations that accept anthropogenic global warming as real and scientifically well-supported:

‘Some sites show cooling’–But you can’t draw global conclusions from individual sites

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: Some stations, in the U.S. for example, show cooling trends. If there were really global warming, it would be warming everywhere.

Answer: Global warming is the long-term increase in globally and seasonally averaged surface temperatures. It is not the case, nor is it expected, that all regions on the planet, let alone all weather stations, will show the same changes in temperature or rainfall patterns. Many stations have shown cooling, and some small regions have shown modest cooling as well. This does not invalidate global warming theory; it is merely the result of regional variation, and an example of how varied and complex the climate system is.

(source: NASA)

‘Climate sensitivity is not very high’–Thermal inertia of the oceans means the jury is still out

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: Taking into account the logarithmic effect of CO2 on temperature, the 35 percent increase we have already seen in CO2 concentrations represents about three-quarters of the total forcing to be expected from a CO2 doubling. Since we have warmed about 0.7 degrees Celsius so far, we should only expect about 0.3 degrees more for a doubling from pre-industrial levels, so about 1 degree total, not 3 degrees as the scientists predict. Clearly the climate model sensitivity to CO2 is much too high.

Answer: Even without addressing the numbers in this argument, there is a fundamental flaw in its reasoning.

It’s time to move on

It's time for everyone to move past the Kyoto Protocol.

For those not familiar with the details, Kyoto imposes specific emission-reduction targets for each industrialized country over a five-year "commitment period" of 2008-2012. Targets were defined for total emissions of CO2 and five other greenhouse gases: the required emission reductions were 8 percent for the European Union and a few other European nations; 7 percent for the United States; 6 percent for Japan and Canada; and zero (i.e. hold emissions at their baseline level) for Russia and Ukraine. If all nations met their targets, the total emission reduction from these nations would be 5.2 percent below 1990 levels.