GEO-4 salutes the world's progress in tackling some relatively straightforward problems, with the environment now much closer to mainstream politics everywhere. But despite these advances, there remain the harder-to-manage issues, the "persistent" problems.
Here, GEO-4 says: "There are no major issues for which the foreseeable trends are favourable." On the urgent issue of climate change, the report says the threat is now so urgent that large cuts in greenhouse gases by mid-century are needed. Negotiations are due to start in December on a treaty to replace the Kyoto Protocol, the international climate agreement that obligates countries to control anthropogenic greenhouse gas emissions.
Although the protocol exempts all developing countries from emission reduction commitments, there is growing pressure on some rapidly industrialising countries -- now substantial emitters themselves -- to agree to emission reductions.
GEO-4 says the world faces an overall crisis that includes climate change, extinction rates, hunger, problems driven by growing human numbers, the rising consumption of the rich and the desperation of the poor. The effects of this crisis are shown in decline of fish stocks, loss of fertile land through degradation or dwindling amount of fresh water available, for example.
The report says climate change is a "global priority", and the response to it demands political will and leadership. Yet UNEP finds "a remarkable lack of urgency", and a "woefully inadequate" global response. Several highly polluting countries have refused to ratify the Kyoto Protocol. GEO-4 says: "Some industrial sectors that were unfavourable to the Protocol managed successfully to undermine the political will to ratify it."
"Fundamental changes in social and economic structures, including lifestyle changes, are crucial if rapid progress is to be achieved," the report points out.
On the issue of water supply, GEO-4 warns that irrigation already takes about 70 percent of available water, yet the world will have to double food production by 2050. "The escalating burden of water demand will become intolerable in water-scarce countries."
Water quality is declining too, polluted by microbial pathogens and excessive nutrients. Globally, contaminated water remains the greatest single cause of human disease and death. In developing countries some three million people die annually from water-borne diseases, most of them under-five-year-olds.
GEO-4 says current biodiversity changes are the fastest in human history. Species are becoming extinct a hundred times faster than the rate shown in the fossil record. Of the major vertebrate groups that have been assessed comprehensively, over 30 percent of amphibians, 23 percent of mammals and 12 percent of birds are threatened.
Yet meeting humanity's growing demand for food will mean either intensified agriculture -- using more chemicals, energy and water, and more efficient breeds and crops -- or cultivating more land. Either way, biodiversity suffers.
The report says environmental exposure causes almost a quarter of all diseases. More than two million people worldwide are estimated to die prematurely every year from indoor and outdoor air pollution. It points out that some of the progress achieved in reducing pollution in developed countries has been at the expense of the developing world, where industrial production and its impacts are now being exported.
According to GEO-4, unsustainable land use is causing degradation, a threat as serious as climate change and biodiversity loss. It affects up to a third of the world's people, through pollution, soil erosion, nutrient depletion, water scarcity, salinity, and disruption of biological cycles.
GEO-4 was prepared by about 390 experts and reviewed by more than 1,000 others across the world.
Decisions that individuals and society make now will largely determine the future of humanity and of the planet, the report says. "Our common future depends on our actions today, not tomorrow or some time in the future."