Juliet Eilperin’s latest headline in the Washington Post (January 29, 2006) about how global warming is destroying the earth was “Debate on Climate Shifts to Issue of Irreparable Change.” The Post, which has been news-editorializing this story for a couple of years now, featured her article above the fold in the top-right corner of the Sunday paper. Obviously they are exercised. Our response: cool it.
Eilperin writes that “the debate has been intensifying because Earth is warming much faster than some researchers had predicted.” Here, she is simply, unalterably, and irrevocably wrong. For the past 30 years—the period during which the earth’s rising temperature has been most strongly associated with human activity—the average rate of warming has been 0.17ºC (or 0.31ºF) per decade (Figure 1). While there is a certain degree of annual variation about this trend, the overall rise has been incredibly steady; in other words, there is no trend to the trend (Figure 2). This means that the earth is warming at a constant, or linear, rate, not one that is accelerating. This is by and large the same behavior that the vast majority of climate models predict the earth’s temperature will display when forced with ever increasing amounts of carbon dioxide (Figure 3). The problem with Figure 3, is that the carbon dioxide growth rate assumed in these models is 1%/year. In reality, the observed growth rate is about half that value, or 0.45%/year (Figure 4). So, we should expect the observed temperatures to be warming up slower than the model projections in Figure 3, and lo and behold, that is precisely what you see (Figure 5). If we extend to observed linear trend into the future, we find that the future temperature rise falls beneath most of the climate model forecasts (Figure 6).
Figure 1. Annual globally averaged temperature anomalies, 1977-2005 (source: Climate Research Unit, http://www.cru.uea.ac.uk/cru/data/temperature/).
Figure 2. Year-to-year change in annual globally averaged temperature anomalies, 1978-2005. There is no statistically significant trend to these data.
Figure 3. Temperature projections from a host of different climate models all run under a scenario of atmospheric carbon dioxide concentrations increasing at a rate of 1%/year (source: Third Assessment Report of the Intergovernmental Panel on Climate Change, http://www.grida.no/climate/ipcc_tar/wg1/fig9-3.htm)
Figure 4. Observed annual growth rate of atmospheric carbon dioxide concentrations, %/year, during the past 30 years. There has been no significant trend in the growth rate during this time. The average value during that time has been 0.45%/year (values derived from data available from the Carbon Dioxide Information Analysis Center, http://cdiac.esd.ornl.gov/trends/co2/sio-mlo.htm)
Figure 5. Same as Figure 3, but with the observed data from Figure 1 superimposed.
Figure 6. Same as Figure 5 but with the trend through the observed data projected into the future.
We’re sorry. Those are the facts, ma’am.
Eilperin claims that the “Earth is warming much faster than some researchers had predicted.” But just who are these researchers? If we turn to the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC)—widely taken as the “consensus of scientists”—we find this chart of temperature projections (Figure 7) and the words “The globally averaged surface temperature is projected to increase by 1.4 to 5.8ºC over the period 1990 to 2100.” That is equivalent to a rise of 0.13 to 0.53ºC (0.23 to 0.95ºF) per decade. Compare that to the observed rate of warming which we’ve established at 0.17ºC (0.31ºF) per decade. Clearly the observations show that the observed rate of warming is running very close to the lowest end of the IPCC warming range. So, we would love to know who are the scientists that Eilperin claims have projected a temperature rise to be occurring slower than 0.17ºC (0.31ºF) per decade? Just name names, please, like a journalist.
Heck, even we don’t argue that the expected warming rate should be much less than the observed warming rate. NASA’s James Hansen has argued that the warming rate over the next 50 years would be 0.15ºC per decade ± 0.05ºC, but when pressed on this low prediction, he stresses that it assumes that some types of (nebulous) emissions slowdown takes place. In any case, 0.17ºC falls neatly into Hansen’s range of 0.10 to 0.20ºC per decade, so he really can’t claim to be surprised. So who then? Nobody who is not labeled as a hardcore “skeptic” thinks that the future warming rate will be much below 0.17ºC anytime in the next several decades.
Figure 7. Temperature projections from the IPCC Third Assessment Report for all the scenarios investigated (source: http://www.grida.no/climate/ipcc_tar/wg1/fig9-14.htm). We have superimposed the projection of the observed data (from Figure 6) onto these IPCC projections.
So, Eilperin appears to making something out of nothing. She sets up a strawman—that it is warming faster than expected—and then proceeds to launch a scare story about how we may be reaching some climate “tipping point” that is irreversible. Whoever said any of this was reversible in the first place? It would be a rather simplistic assumption to think that the earth warms and climate changes as carbon dioxide and other greenhouse gases are added to the atmosphere, and then returns along the same path in the opposite direction when the greenhouse gases are slowly removed from the atmosphere (whenever that is). Sure that might happen, but so might a lot of other things. Atmospheric carbon dioxide emissions are going to continue to grow until major technological advancements take place—advancements that are, at the very least, decades away. So whether or not the climate changes we are observing now are reversible is a non-issue. There is nothing substantive that can be done about it anyway.
Instead, of hyping a non-issue, Eilperin would be doing a far greater service to have reported that the earth’s annual average temperature for the year 2005 fell exactly along the linear trend line established during the past 30 years, and as such, acted to further support the notion that the earth’s temperature is warming up LESS than most people have predicted. Accompanying this slow temperature rise is a slow rise in sea level (the latest predictions are that sea level rise during the 21st century will only be on the order of 12-15 inches, see here or here for more details) and that all of the other over-hyped negative impacts will have to be pared down because they are all directly linked to rate of temperature rise. The less the rate of rise, the lesser the negative impact. This is where Eilperin should have taken her story, but she instead chose the “it’s worse than we thought” route adding further evidence to our rapidly growing collection of media bias reports (see here).