Micronesia is forging new precedent in global environmental law by claiming it is adversely affected by a Czech coal-fired power plant and thus entitled to relief under Czech law.

Micronesia filed a plea with the Czech environment ministry using a measure designed originally to settle disputes between near neighbors, arguing:

The Federated States of Micronesia is seriously endangered by the impacts of climate change, including the flooding of its entire territory and the eventual disappearance of a portion of its state. . . . The commissioning or retrofit of any large coal power plant could play a relevant role in the destruction of the entire environment of our state.

It may be too late for Micronesia. A new study suggests that Antarctica’s Pine Island glacier has passed its tipping point and is poised to collapse in a catastrophe that could raise global sea levels by 24 centimeters.

Pine Island glacier is but one of many at the fringes of the West Antarctic ice sheet. Climate change is warming the Amundsen Sea, which is at the southern margin of the Pacific Ocean. As rising sea levels push the warm water beneath the ice shelves, it melts them from below, pushing the grounding line higher up the continental shelf.

By raising sea levels, and therefore the grounding line, in their model, the scientists identified a point of no return beyond which the glacier would be unable to recover.

The Antarctic sea bed has a small lip in it: it rises slowly up the continental shelf, then makes a slight dip before rising again to the shoreline. The researchers found that as long as the grounding line is on the outer rise of the sea bed, before the lip, small changes in climate lead to correspondingly small changes in the glacier’s ice volume. But as soon as the grounding line moves over the lip and starts to move down into the dip in the sea bed, the situation changes critically. Once the grounding line passes the crest, a small change in the climate causes a rapid and irreversible loss of ice.

News isn’t good from the other pole, either. Scientists at the University of California, Berkeley,  predict that replacing tundra with trees will melt sea ice and greatly enhance warming over the entire Arctic region.

Because trees are darker than the bare tundra, scientists previously have thought that the northward expansion of trees would result in more absorption of sunlight and a consequent local warming.

During past episodes of warming, broad-leaved deciduous trees expanded their range north even more quickly than needle-leaved trees. While not not as dark as evergreen trees, broad-leaved trees transpire a lot more water. Water vapor is a greenhouse gas that becomes well-mixed throughout the Arctic.

Taking account of this in a standard model of global warming, the researchers discovered that, while broad-leaved trees do absorb some additional sunlight, the water vapor they pump into the atmosphere causes a more widespread warming.

The increased water vapor would melt more sea ice, resulting in more absorption of sunlight by the open ocean and dumping more water vapor into the atmosphere. This positive feedback will warm the land even more and encourage faster, more efficient tree growth and perhaps an even faster expansion of trees into the Arctic.