Several studies in the past year have shown that scientists can indeed detect long-term climate change in the rising frequency of extreme events — such as heat waves, heavy rains, severe droughts and strong storms. By using cutting-edge climate models, scientists are not only detecting long-term climate change, but also are attributing at least some of the extreme events to human causes.
The past couple of years have brought a shocking number of extreme events all over the planet. In many cases, short-run natural factors rather than human activity played a role. Last year, for example, La Nina conditions prevailed in the Pacific Ocean. This means that especially warm water was concentrated near Southeast Asia, while colder water was concentrated near Peru. This temporary condition caused many short-term changes in rainfall and temperature patterns leading, for example, to heavy floods in Thailand.
Yet, even after carefully controlling for such natural year-to-year shifts, scientists are also finding that several recent disasters likely reflect human-caused climate change as well. For example, human-caused warming of the Indian Ocean probably played a role in the severe drought in the Horn of Africa last year, which triggered famine, conflict and hunger, affecting millions of impoverished people. The current US mega-drought probably reflects a mix of natural causes, such as La Nina, and a massive heat wave intensified by human-caused climate change.
The evidence is solid and accumulating rapidly. Humanity is putting itself at increasing peril through human-induced climate change. As a global community, we will need to move rapidly and resolutely in the coming quarter-century from an economy based on fossil fuels to one based on new, cutting-edge, low-carbon energy technologies.
The global public is ready to hear that message and to act upon it. Yet politicians everywhere are timid, especially because oil and coal companies are so politically powerful. Human well-being, even survival, will depend on scientific evidence and technological know-how triumphing over shortsighted greed, political timidity and the continuing stream of anti-scientific corporate propaganda.
Jeffrey Sachs is professor of economics and director of the Earth Institute at Columbia University. He is also special adviser to the UN secretary-general on the Millennium Development Goals.
Copyright: Project Syndicate