Introduction:

This addition to the YPCC web site is my effort to provide a resource for those interested in climate change who do not read the scientific literature on climate change. Each month I will summarize my picks of the highlights of climate change science news. I believe it is critical to keep up with the exploding field of climate science to work toward solutions. While this effort innevitably cannot cover all the new scientific evidence coming out, I hope it will still be a useful resource. I welcome feedback.

Background

Three decades of intensive scientific study, hundreds of peer-reviewed journal articles, countless studies, scores of devoted scientists, and untold hours of work have been expended quantifying and understanding global climate change. The vast majority of climatologists now agree that global climate change is underway, and that human activities are the largest contributor. As scientists have learned more, the seriousness and urgency of the threat of global warming has deepened, and current impacts have been measured worldwide. Many scientists and others argue that the time for responding to “climate skeptics” is over. I agree.

It is well known that human activities have caused the more than 30% rise in atmospheric CO2 and other greenhouse gases in the past few centuries, and that this rise is the largest contributor to the climate warming over the past century. There is still debate about the amount and speed that the temperature will rise in the future, due to the complexity of understanding and modeling all the elements that affect climate, but it in no way undermines the validity of the general conclusions.

Those of us working on climate change need to understand current science and be able to communicate about the essential elements of scientific knowledge on climate change. The difficulty is that climate researchers are constantly expanding and refining their understanding of human impacts on global climate.

Climate Science News Highlights - November, 2006

How fast are the ice sheets melting?
Scientists have been discussing and measuring ice sheet melting, particularly at the poles, in recent years. It has far-reaching implications for polar species, and global implications for large and rapid sea level rise. Greenland contains about 10% of global ice mass, and complete melting would raise global sea level by about 6.5 meters. Several recent studies have suggested that Greenland ice melting has accelerated dramatically since 2003. In November, in a study using new analysis techniques, Lutchke et al. confirmed that Greenland ice is melting at an accelerating rate, but suggested the rate may not be as fast as recently suggested in a September paper by Chen et al.. Cazenave (Perspective) discusses some of the reasons for the discrepancies, and calls for more research to improve estimates of ice loss in Greenland and Antarctica.

The take home message is that global warming is melting polar ice sheets, and Greenland ice is now melting at an alarming rate. Remote-sensing data and models have been employed in different ways in each of the studies, resulting in differing results. The Lutchke team found that the Greenland ice sheet has lost about 100 gigatons of ice per year between 2003 and 2005, as compared to the average ice loss rate of about 12 Gt of ice per year for the decade between 1992 and 2002. However, this estimate is much less than other recent rate calculations, which are closer to 240 Gt of ice per year for the same period. Uncertainty remains about the speed of Greenland ice loss.

Species are moving, adapting, and dying due to global warming.
As a conservation biologist, I have been aware for some time of research measuring signals from plants and animals reacting to a warming climate. Entire ecosystems have started to shift, and biologists have been out there quietly, painstakingly documenting the changes. A second major scientific story about global climate change came out in the Annual Review of Ecology, Evolution, and Systematics in November. In her paper, “Ecological and Evolutionary Responses to Recent Climate Change,” Camille Parmesan reviews the recent scientific literature quantifying the effects of global warming on living things. She reviews 866 studies, and finds evidence that climate change has affected species worldwide, in all taxonomic groups and all ecosystems. Other studies have described specific problems faced by species, populations, or areas affected by climate change, but this is the first comprehensive analysis of the planet-wide impacts of global warming on living things.

It is hard to overstate the scope of the impacts she documents. This review describes ecological changes in phenology and distribution of plants and animals in all well-studied marine, freshwater, and terrestrial groups. These observed changes are heavily biased in the directions predicted from global warming and have been linked to local or regional climate change through correlations between climate and biological variation, field and laboratory experiments, and physiological research. The most negatively affected groups include range-restricted species, particularly polar and mountaintop species, tropical coral reef organisms, and amphibians. Impacts include changes in predator-prey and plant-insect interactions, evolutionary adaptations to warmer conditions, observed genetic shifts, and extinction of entire species.

For a pdf of the full article, go to:
http://cns.utexas.edu/communications/File/AnnRev_CCimpacts2006.pdf