Mar 27 2010

Global Warming Contrarians Part 5: Counting Carbon

This is the latest instalment in a continuing series of posts on the (mostly bad) arguments that contrarians make against global warming. A list of earlier parts in the series can be found at the bottom of this post.

Claim: Natural CO2 emissions far outweigh our own.

Fact: This claim is true but misleading. Before the Industrial Revolution, natural emissions of 698 Gt/yr were balanced by natural absorptions of 698 Gt/yr (neglecting volcanic emissions, which make no significant difference on human timescales):

Average CO2 emissions and absorptions circa 1750. All figures are in gigatonnes of CO2 (GtCO2); to convert to gigatonnes of carbon (GtC), multiply by 3/11. (Simplified version of IPCC AR4 WGI Figure 7.3)

Human emissions are indeed much lower than natural emissions (for 2000-2008, 28.1 Gt/yr from fossil fuels and 5.3 Gt/yr from land use change), but they are not balanced by natural absorption, so the CO2 has been building up in the atmosphere: Continue reading

Mar 23 2010

Global Warming Contrarians Part 4: Back to Basics

So far in my series of posts on the arguments contrarians make against global warming, I’ve written about the changes being observed in the Earth’s climate. I wrote about whether the global temperature has increased (short answer: yes); whether it has recently stopped increasing (short answer: probably not); and whether ice is declining around the world (short answer: yes). Now I figure it’s time to go back to where it all begins: with CO2 and the greenhouse effect.

Claim: The greenhouse effect does not exist.

Fact: The greenhouse effect is as established a phenomenon as any. It was first discovered in the 1820s by French mathematician Joseph Fourier, and the basic physics was essentially understood by the 1950s. Greenhouse gases are completely transparent to visible light but less so to infrared. Visible sunlight is transmitted through the Earth’s atmosphere and warms the surface, causing Earth to emit infrared light (because Earth is much cooler than the Sun, its radiation peaks at a lower wavelength). But on the way out, some of this radiation is trapped by greenhouse gases, which reflect it back to Earth and make the surface warmer. If it were not for the greenhouse effect, the Earth’s average surface temperature would be about 33°C colder.

Claim: CO2 is not evil/not a pollutant.

Fact: The “straw person” fallacy is committed when one (intentionally or otherwise) misrepresents the argument one is attempting to counter. “CO2 is not evil” could be a textbook example. Of course there is nothing inherently evil about carbon dioxide — but nobody is claiming that there is. It’s just another molecule. Continue reading

Mar 13 2010

Global Warming Contrarians Part 3: Hiding the Decline of Ice

In 2007, the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) concluded that global warming is unequivocal, and that serious impacts of global warming are already beginning to occur. The AR5 isn’t due until 2013, but in 2009, a non-IPCC report called the Copenhagen Diagnosis was released to provide an update on the AR4. The authors found more evidence that various impacts were occurring, many of them at an increasing rate.

This is the third in a series of posts on the arguments contrarians make against global warming. In Part 1, I discussed whether the global temperature had increased (short answer: yes). In Part 2, I discussed whether it had recently stopped increasing (short answer: probably not). I know I promised a post about the hockey stick, but that is turning out to be more difficult to write about than I thought it would be; so in the meantime, here is a piece about one impact of global warming.

Claim: Ice sheets, glaciers, and sea ice are not melting.

Fact: All of the above are melting.

The Gravity Recovery and Climate Experiment (GRACE) satellites, launched in 2002, are able to measure gravity so sensitively they can detect changes in the mass of ice sheets (huge layers of land ice). GRACE measurements show that since 2002, the Antarctic ice sheet has been losing mass at an accelerating rate.

Antarctica has been losing 190 Gt/yr of ice since 2002. (Source: NASA)

Continue reading

Mar 04 2010

Did Spanish Astronomers Steal A Dwarf Planet?

In 2005, a controversy erupted in the world of astronomy over who should be credited with the discovery of a distant dwarf planet then known by the temporary name 2003 EL61. The object in question is located in the Kuiper Belt, a doughnut-shaped icy region of the solar system that lies beyond Neptune. It is classified as a “dwarf planet” — which, counter-intuitively, is not actually a planet. According to the International Astronomical Union (IAU), the official naming body in astronomy, a planet must

(a) orbit the Sun,

(b) be massive enough to have a spherical shape,

(c) be massive enough to dominate its region of the solar system, and

(d) not be a moon.

Dwarf planets are almost planets but not quite – they satisfy criteria (a) and (b), but not (c). There are four other objects officially classified as dwarf planets (although many more may qualify): Ceres, the largest object in the asteroid belt between Mars and Jupiter; Pluto, a large Kuiper Belt Object (KBO); Makemake, another large KBO; and Eris, a large object in the region beyond the main Kuiper Belt, the scattered disk.

Pluto has been known for decades and Ceres for centuries, but Eris and Makemake are much more recent finds, discovered in 2005 by a group of astronomers led by Mike Brown at the Department of Geological and Planetary Sciences at Caltech. As for 2003 EL61, not only has Brown’s team claimed its discovery, but so has a rival team led by Jose-Luis Ortiz of the Andalusian Astrophysics Institute in Granada, Spain. Continue reading

Feb 20 2010

Global Warming Contrarians Part 2: 1998, El Niño, and Ocean Heat Content

This is the second in a series of posts on the arguments contrarians make against global warming. In Part 1, I discussed long-term global temperature trends, criticisms of the surface temperature record, and cold weather. And without further ado, I’ll continue by looking at another popular claim about global temperatures…

Claim: Global warming stopped in 1998.

Fact: The warmest year on record is 2005 (14.52°C, or 0.62°C above the 20th century average), followed by 1998 (14.50°C). But this does not mean the Earth has been cooling since 1998. 2009 came in at sixth warmest (14.46°C), the years 2001-2009 all make the top ten, and the top 14 have all occurred since 1995 — so at the very least, we can say the Earth hasn’t cooled. The 2000s was the warmest decade (14.44°C), followed by the 1990s (14.26°C) and 1980s (14.10°C).*

Average global temperatures for each decade on record compared to each year. (Source: NCDC)

Continue reading

Feb 13 2010

Why the Global Warming “Skeptics” Are Wrong – Part 1: Tracking Temperatures

Mark Twain once said, or at least is supposed to have said: “A lie can travel halfway around the world while the truth is putting on its shoes.” The climate change contrarian blogosphere that has recently emerged is rather like that. Every month, there is some new argument being passed around that “disproves” global warming or the integrity of climate science in general, and it is amplified in blogs and opinion columns worldwide. These global-warming-disproved memes seem to have had something of a revival recently, which is ironic considering that the scientific evidence, if anything, has moved in the opposite direction: the evidence for global warming is now stronger, and more alarming, than ever.

This will be the first in a series of posts on the arguments contrarians make against global warming.

Claim: The Earth isn’t warming.

Fact: The Earth’s surface has warmed about 0.72°C in the last century, and about 0.18°C/decade in the last quarter-century.* Before the 1970s, the trend was much slower and disguised by large fluctuations, including a slight cooling in the mid-20th century (which I’ll discuss in a future post). Continue reading