Scientists have already shown significant alteration of the American landscape because of increased CO₂ emission from burning fossil fuel, which causes global warming. But, pressured by various lobbies (mainly oil and auto industries), the US government has been dragging its feet over acknowledging that global warming is indeed a serious threat.

Until now, that is. Bowing to a district court judge’s ruling that the government must produce the latest scientific assessment of global warming by May 31, the Climate Change Science Program, which was commissioned by USDA and integrates the federal research efforts of 13 agencies on climate and global change, released its findings on May 27.

The study, which was carried out by 38 scientists from inside the government and outside (universities, national laboratories and non-governmental organizations), includes no new research, but synthesizes a thousand scientific papers to highlight how the human-generated CO₂ emission has already caused major changes in our environment.

From the press release, the main points of the study are:

1. Increasing temperatures will increase the risk of crop failures, particularly if rainfall decreases and/or becomes more unpredictable.
2. Higher temperatures will reduce productivity of livestock and dairy animals, and greater mortality will offset the reduced mortality in warmer winters.
3. Climate change has already increased the size and frequency of forest fires, insect outbreaks and tree mortality, in the forests of interior West, Southwest and Alaska. These effects will continue.
4. The West and Southwest have also experienced increased draught conditions.
5. Weeds grow more rapidly under high atmospheric CO₂, and they are expected to migrate northward and be resistant to herbicides.
6. Invasion by exotic grass species into arid lands will increase, causing higher fire frequency, which in turn will affect rivers and riparian systems in these areas.
7. Horticultural crops (tomato, onion, fruit) are more sensitive to climate change than grains and oilseed crops.
8. The length of the growing season has increased by 10 to 14 days over the last 19 years across the temperate latitudes, and species distributional ranges have shifted as a result.
9. Arctic snow and ice covers have dramatically declined because of warming, and the resulting habitat loss is threatening the wildlife, such as the polar bear, that depend on ice.

Polar bear was declared a threatened species last Wednesday (May 14) by US Interior Department. This was long time coming, given that the Arctic sea ice, polar bear’s primary habitat, is melting at a rate of 10% each decade over the last three decades - a loss of about 28,000 square miles a year!

According to US Fish and Wildlife Service Department, the agency that administers the Endangered Species Act (ESA), an endangered species is one that is in danger of becoming extinct over its entire (or major part of) range, and a threatened species is one that is likely to become endangered in near future.

Polar bear population across the Arctic from Alaska to Greenland more than doubled, from about 12,000 to 25,000, since 1960. But, a US Geological Survey study last year suggests that sea ice loss would cause a population decline of about 15,000 bears in coming decades, and about two-third by mid-century.

Polar bears depend completely on the ice surface - they walk, hunt, nest and breed on the surface of Arctic ice. Their main food consists of ringed and bearded seals, which come on ice only to give birth. So, bears must be on ice to successfully hunt them. This is a telling example of the damaging effect of habitat loss, currently ranked as the biggest threat to global biodiversity.

The problem with this particular example, according to many who are skeptical that the listing will lead to any significant action, is the thorny political issue of global warming that is melting the ice in the first place. The interior secretary is already quoted as saying that the ESA “is not the right tool to set US climate policy”, and “the listing will not stop global climate change or prevent any sea ice from melting”.

In other words, the government, while admitting that the polar bear is at a danger and needs protecting, would rather take short-term steps to protect isolated bear populations (stop bear hunting, for example), than reduce global warming, which would not only help protect bear habitat and ensure their long-term safety, but also save many other species that will otherwise be in similar peril, today or tomorrow.