Some 25 million people have already been forced to leave their homes due to environmental problems. That number, according to a report by Tearfund, a UK-based relief and development agency, could become as high as 200 million by mid-century as the impacts of climate change cause water shortages around the world.

Humans will need two Earths by 2050 if present trends in natural resource consumption continue. Currently, our use of ecosystem goods and services such as food, timber, energy, and waste recycling exceeds the planet's ability to provide them--its biocapacity--by 25 percent.

In 2005, natural disasters affected 150 million people and caused US$159 billion in damages. Several resources produced by the World Bank and its partners have identified natural disaster "hotspots"--places most exposed to environmental catastrophes--in order to prioritize funding and promote sustainable development initiatives that mitigate disaster risk and enable communities to recover more quickly.

In many developing countries, 80-90% of human sewage entering the marine environment is untreated. Large numbers of people, particularly in East Asia, have risen out of economic poverty in recent years, but waste treatment infrastructure has not been able to keep pace with rapidly growing coastal populations. China, for example, has a coastal population of around 300 million (roughly the size of the entire United States), yet has the capacity to treat only 25% of all its wastewater and sewage.

The Food and Agriculture Organization's annual observance of World Food Day on 16 October draws global attention to the approximately 850 million people worldwide who are undernourished. This year's events focus on "investing in agriculture for food security," in addition to the needs for improving education and health systems.

Some 2 million people die prematurely every year due to indoor and outdoor air pollution. The World Health Organization (WHO) has released a new set of Air Quality Guidelines in an effort to compel national governments to more effectively curb emissions of major air pollutants and protect human health.

Approximately 1.2 billion people gained access to safe drinking water and improved sanitation facilities between 1990 and 2004 according to a recent report by UNICEF. Current trends place the world on track to meet the access to drinking water target established in the Millennium Development Goals, but show that the world is not on track to achieve the sanitation target.

Focusing on youth, aged 12-24, the World Bank's 2007 World Development Report: Development and the Next Generation urges developing nations to invest in education, healthcare, and employment initiatives for this critical demographic in order to promote future economic growth and reduce poverty.

In the middle of the twentieth century, Asia and Latin America experienced an agricultural transformation. Holistic agricultural development programs initiated by governments and philanthropists created new varieties of higher-yielding seeds, improved planting methods through farmer education, and enhanced infrastructure and trade to facilitate the processing and transport of agricultural goods. Known as the "Green Revolution," these efforts utilized climate, soil, and resources to double and even triple food production, saving millions from hunger and poverty.

A new study of global temperature change reports that Earth's surface has warmed at a rate of approximately 0.2°C (0.36°F) per decade during the past thirty years, pushing temperatures to their highest levels in the last 12000 years. The study (Hansen et al., 2006) also provides evidence that global warming of another 1°C could result in more significant climate change impacts, including rapid sea level rise, wide-spread biodiversity loss, and an increased intensity of El Niño events.