A Changing Pace
Weather happens hour by hour, day by day—it’s a thunderstorm, a heat wave, a windy afternoon. Taken as averages over decades and centuries, those patterns of precipitation, temperature, and wind for a given region comprise our climate.
For as long as Earth has existed, such climate conditions at specific sites have shifted over long periods of time. However, within the last century, climatic shifts — extreme weather of all sorts, including droughts, heat waves, hurricanes, and higher sea levels — have accelerated at an unprecedented rate. The result: Climate change, which will affect many aspects of our way of life, including food access, water distribution, air quality, and more.
The Role of CO2
Scientific evidence points to rising levels of carbon dioxide (CO2) and other greenhouse gases as the most significant contributor to climate change. While some greenhouse-gas emissions are naturally occurring, the exponential increase in recent decades, generated in large part by human activities — think burning fossil fuels and deforestation — interferes with the planet’s atmosphere. Atmospheric levels of CO2 have risen dramatically since 1950 and have reached a level far beyond historical cycles, going back over 400,000 years. More CO2 means more climate change. Like a blanket, CO2 traps solar heat within the atmosphere, shifting how much moisture evaporates from the oceans, how much falls as snow or rain and in what parts of the world, and the rate at which ice on the polar caps melts. Additionally, as ice caps melt, methane (CH4) trapped in the ice, and in permafrost, will be released into the atmosphere, while disappearing ice will cause the ocean and land to absorb more heat, because the ice acts as a shield from the sun. Both of these effects with further accelerate ice melt. These, and other compounding contributing factors will increase the rate at which global temperatures rise, and thus will increase climate change.
It’s All In The Numbers
Scientists first recognized the possibility of human influence on the climate system around the '60s — the 1760s — that is, the beginning of the Industrial Revolution. While climatologists began documenting subtle shifts around then, the most extreme evidence of climate change has accumulated since the mid-1950s. In the United States, torrential rainfall, wildfires, drought, heat waves, and floods have all become more intense and more frequent.
In 2010, the National Research Council called on the United States to act immediately to reduce greenhouse-gas emissions and develop a national plan to adapt to the inevitable results of a changing climate.
What It Means
As climate changes further, scientists forecast that precipitation trends will intensify, with the northern United States becoming wetter, while states in the South — especially in the Southwest — will experience even more intense droughts. On the coasts, plan for increasingly severe hurricanes with flooding and storm surges. Nationwide, scientists forecast that the average US temperature will rise by 4 to 11 degrees Fahrenheit. In Southern states, that could translate to 150 days every year when the mercury rises above 90 degrees Fahrenheit.
Such shifts have effects on the food supply as farmers respond to increasingly erratic temperatures and rainfall patterns during the growing season. Consider, for example, the shifting date of peak cherry bloom in our nation’s capital — now five days earlier, on average, than it was in the 1920s.
Other aspects of climate change have more profound consequences for wildlife and humans. For example, polar bears in Canada’s Hudson Bay now have diminished access to the ice from which they usually hunt — threatening the species with extinction. Ducks, geese, other water birds, and monarch butterflies, are all shifting their migration patterns in response to extreme droughts and floods. Humans, too, are feeling the effects of extreme weather. Populations of mosquitoes, ticks, and other disease carriers are shifting and growing due to weather changes that allow these insects to thrive, increasing the risk of diseases like West Nile virus and Lyme disease in the United States. Some areas of the world are experiencing intense heat and widespread drought, while others are suffering from torrential rains and frequent flooding, which affects local agriculture and public health.
Plan of Action
The small choices we make every day can influence global emissions. Look for ways to reduce consumption whenever possible — for example, choose high-efficiency appliances and light bulbs with the Environmental Protection Agency’s ENERGY STAR label. When contemplating a new purchase, embrace the mantra “reduce, reuse, recycle” to minimize what’s hauled to your community’s landfill. Extend the concept to the kitchen by turning food and lawn waste into compost; while landfills generate high amounts of greenhouses gases from rotting waste, composting turns organic waste into nutrient-rich soil. On the road, opt to walk, bike, or use public transportation whenever possible. And if you must drive, consider a carpool, and practice regular maintenance to optimize your vehicle’s fuel efficiency.
- National Oceanic and Atmospheric Administration
- National Wildlife Federation
- U.S. Environmental Protection Agency
- World Health Organization
- US Global Change Research Program
- Environmental Defense Fund