News stories by Analysis by Lester R. Brown*

Between 2007 and 2011, carbon emissions from coal use in the United States dropped 10 percent. During the same period, emissions from oil use dropped 11 percent.

Many countries are facing dangerous water shortages. As world demand for food has soared, millions of farmers have drilled too many irrigation wells in efforts to expand their harvests. As a result, water tables are falling and wells are going dry in some 20 countries containing half the world's people.

Heat waves clearly can destroy crop harvests. The world saw high heat decimate Russian wheat in 2010. Crop ecologists have found that each one-degree Celsius rise in temperature above the optimum can reduce grain harvests by 10 percent. But the indirect effects of higher temperatures on our food supply are no less serious.

One key component of the Plan B climate stabilisation strategy is solar energy. Solar is even more ubiquitous than wind energy and can be harnessed with both solar photovoltaics (PV) and solar thermal collectors.

When it comes to population growth, the United Nations has three primary projections. The medium projection, the one most commonly used, has world population reaching 9.2 billion by 2050. The high one reaches 10.5 billion. The low projection, which assumes that the world will quickly move below replacement-level fertility, has population peaking at eight billion in 2042 and then declining.

Uprisings in Tunisia, Egypt, and across the Middle East at the start of 2011 have reminded the world just how politically fragile some countries are. But the focus of international politics has been shifting for some time now.

The bicycle has many attractions as a form of personal transportation. It alleviates congestion, lowers air pollution, reduces obesity, increases physical fitness, does not emit climate-disrupting carbon dioxide, and is priced within the reach of the billions of people who cannot afford a car.

With water shortages constraining food production growth, the world needs an effort to raise water productivity similar to the one that nearly tripled land productivity over the last half-century.

Cars promise mobility, and in a largely rural setting they provide it. But in an urbanising world, where more than half of us live in cities, there is an inherent conflict between the automobile and the city.

The past two years have witnessed the emergence of a powerful movement opposing the construction of new coal-fired power plants in the United States. Initially led by environmental groups, both national and local, it has since been joined by prominent national political leaders and many state governors.