Outgrowing the Earth Part 9




EARTHSCAN          2005


Chapter 7: Stabilizing Climate

In July of 2004, the US National Academy of Sciences released a research report by a team of nine scientists from China, India, the Philippines, and the United States who had measured the precise effect of rising temperatures on rice yields under field conditions. They concluded that yields typically fall by 10% for each 1-degree Celcius rise in temperature during the growing season. This confirmed what had seemed obvious to many agricultural analysts, namely that high temperatures can shrink harvests.

  • In recent years, numerous heat waves have lowered grain harvests in key food-producing countries.
  • Farmers already struggling to feed 70 million or more people each year will find it even more difficult as the earth’s temperature rises.


Rising temperatures, falling yields

  • Within just the last few years, crop ecologists in several countries have been focusing on the precise relationship between temperature and crop yields.
  • The IRRI team of eminent crop scientists noted that from 1979 to 2003, the annual mean temperature at the research site rose by roughly 0.75 degrees Celcius.
  • The team’s finding confirmed the rule of thumb emerging among crop ecologists – that a 1-degree-Celcius rise in temperature lowers wheat, rice, and corn yields by 10%.
  • They concluded that “temperature increases due to global warming will make it increasingly difficult to feed the earth’s growing population.”

An empirical analysis of the effect of temperature on corn and soybean yields was conducted in the United States. It concluded that higher temperatures had an even greater effect on yields of these crops. Using data for 1982-98 from 618 counties for corn and 444 counties for soybeans, David Lobell and Gregory Asner concluded that for each 1-degree Celcius rise in temperature, yields declined by 17%. Given the projected temperature increases in the US Corn Belt, where a large share of the world’s corn and soybeans are produced, these findings should be of grave concern to those responsible for world food security.

  • What the new research shows is that the negative effect of higher temperature on crop yields overrides the positive effect of higher CO2 levels.  Indeed, if pollination fails and there is no seed formation, then the CO2 effect on grain yields is lost entirely.
  • As temperatures rise, crop withering heat waves are becoming more and more common.


Temperature trends and effects

  • Since 1970, the earth’s average temperature has risen by 0.7 °C, or 1.3 °F. each decade the rise in temperature has been greater than in the preceding one.
  • Four of the six warmest years since record-keeping began in 1880 have come in the last six years.
  • Two of these, 2002 and 2003, were years in which the major food-producing regions saw their crops wither in the presence of near-record temperatures.

Atmospheric concentrations of CO2, estimated at 280 ppm when the Industrial Revolution began, have been rising ever since people in Europe began burning coal. They have risen every year since precise measurements began in 1959, making this one of the world’s most predictable environmental trends. As shown in Figure 7-2, atmospheric CO2 concentrations turned sharply upward around 1960. Roughly a decade later, around 1970, the temperature too began to climb; the rise since than is quite visible in Figure 7-1. Projections by the Intergovernmental Panel on Climate Change (IPCC) show temperatures rising during this century by 1.4 – 5.8 degrees Celcius. The accelerating rise in temperature in recent years appears to have the world headed toward the upper end of that projected range of increase.

  • The warming will be greater over land than over the oceans, in the higher latitudes than in the equatorial regions, and in the interior of continents than in the coastal regions.
  • One of the higher increases is expected to be in the interior of North America – an area that includes the grain-growing Great Plains of the United States and Canada and the US Corn belt, the very region that makes this continent the world’s breadbasket.

One of the major concerns among scientists today is the accelerated melting of the Greenland ice sheet. If the ice sheet on Greenland – an island three times the size of Texas – were to melt entirely, sea level would rise 7 meters (23 feet), inundating not only Asia’s rice-growing river deltas and flood plains but most of the world’s coastal cities as well. This kind of massive melting, even in the case of the most rapid warming scenario, would occur over centuries, however, not years.

  • The World Bank has published a map of Bangladesh, which shows that a 1-meter rise in sea level would inundate half of the country’s riceland. It would also displace some 40 million Bangladeshis. Where would these people go?


Raising energy efficiency

If rising temperatures continue to shrink harvests and begin driving up food prices, public pressure to stabilize climate by cutting the carbon emissions that cause the greenhouse effect could become intense. The goal is to cut these emissions enough to stabilize climate and eliminate the threat to world food security from rising temperatures. Cutting emissions enough to stabilize atmospheric CO2 levels is an ambitious undertaking, but given the technologies now available to both raise energy efficiency and develop renewable sources of energy, it can be done – and quickly, if need be.

  • A few examples of how to cut the use of oil and coal, the principal sources of carbon emissions, will illustrate the possibilities.
  • Motorists can reduce oil use dramatically by shifting to cars with hybrid gas-electric engines. This opens up two exciting additional possibilities
  • The first is to modestly expand the electrical storage capacity of the hybrids by adding a second battery.
  • The second is to include a plug-in recharge capacity so that owners can recharge their car batteries at night.
  • Adding a second battery and a plug-in capacity could reduce gasoline use by perhaps another 20%, for a total reduction in US gas use of 70%.

These two modest technological modifications lead to an exciting possibility on the supply side, namely the use of cheap wind-generated electricity to power automobiles. Does the United States have the wind power potential to do this? As described later in this chapter, it has enough harnessable wind power to meet its electricity needs several times over.

  • It would be a simple matter to replace the widely used old-fashioned, highly inefficient, incandescent light bulbs with compact fluorescent lamps that provide the same light but use less than a third as much electricity.
  • A worldwide decision to phase out incandescent light bulbs would allow literally hundreds of coal-fired power plants to be closed.
  • Not only would this help stabilize climate, but the return on investment in the new bulbs in the form of lower electricity bills is roughly 30% a year.


Turning to renewable energy sources

There are also many options for cutting emissions by harnessing renewable sources of energy, including wind energy, geothermal energy, and biomass.

  • As this chapter aims simply to give a sense of the possibilities for cutting carbon emissions, the discussion here will focus on wind as a renewable source of energy.
  • The use of wind power is growing fast because it is abundant, cheap, inexhaustible, widely distributed, clean, and climate-benign – a set of attributes that no other energy source can match.
  • North Dakota, Kansas, and Texas alone have enough harnessable wind energy to satisfy national electricity needs.
  • Design advances enable turbines to operate at lower speeds, to convert wind into energy more efficiently, and to harvest a much larger wind regime.
  • Many of the other 47 states are richly endowed with wind energy.

Europe is the model for developing wind power. Although its wind resources are modest compared with those of the United States, it is moving much faster to harness them. In its late 2003 projections, the European Wind Energy Association (EWEA) shows Europe’s wind-generating capacity expanding from 28,400 megawatts in 2003 to 75,000 megawatts in 2010 and then 180,000 megawatts in 2020. By 2020, just 16 years from now, projections show that wind-generated electricity will be able to satisfy the residential needs of 195 million Europeans, half of the region’s population.

  • When the wind industry first began to develop in California, wind-generated electricity cost 38 cents per kilowatt hour. Since then it has dropped to 4 cents or below in prime world sites.
  • EWEA projects that by 2020 many wind farms will be generating electricity at 2 cents per kilowatt-hour, making it cheaper than other sources of electricity.
  • Europe is not only leading the world into the wind age, it is also leading the world into the post-fossil-fuel-age – the age of renewable energy and climate stabilization.

The impetus for that new energy economy to unfold quickly may come from an unexpected source: agriculture. The effect of rising temperatures on crop yields fundamentally broadens the responsibility for food security. Historically, food security was the sole responsibility of the Ministry of Agriculture, but now the Ministry of Energy also bears responsibility. Decisions made by ministries of energy on whether to stay with carbon-based, climate-disrupting fossil fuels or to launch a crash program to develop renewables may have a greater effect on food security than do any of the decisions made in the ministries of agriculture

Data for figures and additional information can be found at www.earth-policy.org/Books/Out/index.htm

Chapter 8: Reversing China’s Harvest Decline

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