Global Warming: Why a Couple Degrees Makes All the Difference



What’s the big fuss over 2 degrees Celsius? That’s the temperature increase to which 195 countries agreed to limit global warming at the 2015 Paris climate talks. And it would seem to be trivial. A 2-degrees-Celsius (3.6 degrees Fahrenheit) increase from 4.4 to 6.4 Celsius (40-43.6 Fahrenheit), after all, doesn’t have us shedding our Shetland sweaters for shorts and a tank top. It won’t make us declare that spring is here or moan about the sizzling heat of summer. We barely notice it.

The truth, however, is that for the last 10,000 years — the time of all human civilization and more — global temperatures have fluctuated by only around one degree Celsius. By comparison, the fast-paced industrialization of the last century has brought increases of nearly three-quarters of that, or 0.7 degrees. That is a rate roughly ten times faster than what the planet experienced during the 5,000 years of its emergence from the last ice age. A 4 degree (7.2 degree Fahrenheit) increase, which the United Nations Intergovernmental Panel on Climate Change believes entirely possible by 2100, would put us near the 4.5-7 degree temperature rise that separates us from an era when much of Europe and the United States was an icy waste.

The earth’s physical and biological processes are extremely fragile and sensitive to temperature, and we already are seeing the transformation to a warmer world. In Central America, the number of hurricanes has climbed from 15 in the 1980s to more than 35 since the beginning of the century. Drought has crippled hydroelectric production in Venezuela and Brazil. It has wiped out huge quantities of cattle and wildlife in Colombia. Andean glaciers are 15% smaller, and the great Mesoamerican coral reef, stretching 1,100 kilometers from the Yucatan Peninsula to the Honduran Bay Islands, is under siege from ocean warming and carbon-dioxide acidification, threatening hundreds of marine species.

As temperatures continue to rise things will likely get much worse because even small increases can make a big difference. More than 450 million people in Latin America and the Caribbean live within 200 kilometers of the coast. A 2014 report by the United Nations’ Intergovernmental Panel on Climate Change warns that storm surges and flooding, not including hurricanes, will become more dramatic, with the Rio de La Plata Region of Argentina and Uruguay particularly hard hit. The Mesoamerican coral reef could collapse altogether by mid-century, causing annual losses in the hundreds of millions of dollars in tourism, fisheries and coastal protection to Belize alone. Losses in crop productivity of corns, bean and rice, together with an intensification of disease affecting coffee bushes, could be especially devastating in Central America. They could, according to the report, affect the poorest people there, increasing rates of chronic malnutrition.

Cities will not be exempt. As revealed in a recent blog and IDB study, large-scale, climate-triggered migrations from the countryside to urban centers threaten to spur emissions as more people have access to electronics and energy-intensive appliances. That, in turn, would stoke global warming’s effects and add stress to everything from transport to health and education facilities. Food services, insurance carriers, retail, wholesale and real estate, may be battered as well. As explained in another recent blog and IDB study a 1 degree Fahrenheit increase in average summer temperatures in the United States between 1997-2011 decreased the growth rate of the retail sector by .241 percentage points and the food services and drinking places sector by .387 points.

The region already is working to develop heat-resistant species of plants and more efficient irrigation systems. Extensive reforestation campaigns are helping preserve water resources. And cleaner and more efficient transportation systems have been implemented from Bogotá to Curitiba. But the construction of buildings that use less energy and the strengthening of sea walls, as well as a host of other adaptation measures, are still urgently needed in many places to confront the challenges ahead.

Ultimately, the struggle for the region and the rest of the world is to keep carbon emissions down. Scientists overwhelmingly agree that given emissions-reductions commitments in Paris, the world will be unable to limit rising temperatures to the 2-degree-increase commitment this century. It could hit a 1.5 degree increase within a decade. A 2-degree-increase, it turns out, is no trifle. It is but one station on the road to a possible 4 degree warming and catastrophe this century unless the international community dramatically boosts its efforts.


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The Author

Bridget Hoffmann

Bridget Hoffmann

Bridget Hoffmann is an economist in the Research Department of the Inter-American Development Bank. Her research interests are applied microeconomics, development economics, and environmental economics. She received her Ph.D. in Economics from Northwestern University in 2015. She holds a bachelor’s degree in Financial Economics and Mathematics from the University of Rochester.

The Author

Steven Ambrus

Steven Ambrus worked as a correspondent for US and European media during two decades in Latin America, covering politics, education, the environment and other issues. He currently works in the communications and publications unit of the Research Department at the IDB.

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