COURTESY   :  www.nrdc.org/

CLIMATE CHANGE

Climate change is generally defined as a significant variation of average weather conditions—say, conditions becoming warmer, wetter, or drier—over several decades or more. It’s the longer-term trend that differentiates climate change from natural weather variability.

Record floods. Raging storms. Deadly heat. Climate change manifests itself in myriad ways and is experienced by every living being, although not equally. Throughout the world, the economically disadvantaged and people of color—those who have contributed the very least to the root causes of climate change—are the most likely to suffer from its worst impacts. Here are the basics on what causes climate change, how it’s affecting the planet and its people, and what we can do about it.

How Is Climate Change Measured Over Time?

Climate refers to the general weather conditions of a place as measured over many years. In the United States, for example, Maine’s climate is cold and snowy in winter while South Florida’s is tropical year-round.

Earth-orbiting satellites, remote meteorological stations, and ocean buoys are used to monitor present-day weather and climate, but it’s paleoclimatology data from natural sources like ice cores, tree rings, corals, and ocean and lake sediments that have enabled scientists to extend the earth’s climatic records back millions of years. These records provide a comprehensive look at the long-term changes in the earth’s atmosphere, oceans, land surfaces, and cryosphere (frozen water systems). Scientists then feed this data into sophisticated climate models that are able to predict future climate trends with impressive accuracy.

It’s worth noting that while climate change and global warming are often used interchangeably, global warming—the recent rise in the global average temperature near the earth’s surface—is just one aspect of climate change.

What Causes Climate Change?

The mechanics of the earth’s climate system are simple. When energy from the sun is reflected off the earth and back into space (mostly by clouds and ice), or when the earth’s atmosphere releases energy, the planet cools. When the earth absorbs the sun’s energy, or when atmospheric gases prevent heat released by the earth from radiating into space (the greenhouse effect), the planet warms. A variety of factors, both natural and human, can influence the earth’s climate system.

Natural causes of climate change

The earth has gone through warming and cooling phases in the past, long before humans were around. Forces that can contribute to climate change include the sun’s intensity, volcanic eruptions, and changes in naturally occurring greenhouse gas concentrations. But records indicate that today’s climatic warming—particularly that which has occurred since the mid-20th century—is happening at a much faster rate than ever before, and it can’t be explained by natural causes alone. According to NASA, “[t]hese natural causes are still in play today, but their influence is too small or they occur too slowly to explain the rapid warming seen in recent decades.”

Anthropogenic causes of climate change

Humans—more specifically, the greenhouse gas (GHG) emissions that human activity generates—are the leading cause of the earth’s rapidly changing climate today. Greenhouse gases play an important role in keeping the planet warm enough to inhabit. But the amount of these gases in our atmosphere has skyrocketed in recent decades. According to the U.S. Environmental Protection Agency, our current concentrations of carbon dioxide, methane, and nitrous oxide “are unprecedented compared with the past 800,000 years.” Indeed, the atmosphere’s share of carbon dioxide—the planet’s chief climate change contributor—has risen by 46 percent since preindustrial times.

The burning of fossil fuels like coal, oil, and gas for electricity, heat, and transportation is the primary source of human-generated emissions. A second major source is deforestation, which releases sequestered (or stored) carbon into the air. It’s estimated that logging, clearcutting, fires, and other forms of forest degradation release an average of 8.1 billion metric tons of carbon dioxide per year, accounting for more than 20 percent of all global CO2 emissions. Other human activities that generate air pollution include fertilizer use (a primary source of nitrous oxide emissions), livestock production (cattle, buffalo, sheep, and goats are major methane emitters), and certain industrial processes that release fluorinated gases. Activities like agriculture and road construction can also change the reflectivity of the earth’s surface, leading to local warming or cooling.

Though our planet’s forests and oceans absorb greenhouse gases from the atmosphere through photosynthesis and other processes, these natural carbon sinks can’t keep up with our rising emissions. The resulting buildup of greenhouse gases is causing alarmingly fast warming worldwide. It’s estimated that the earth’s average temperature rose by about 1 degree Fahrenheit during the 20th century. If that doesn’t sound like much, consider this: When the last ice age ended and the northeastern United States was covered by more than 3,000 feet of ice, average temperatures were just 5 to 9 degrees cooler than they are now.

The Effects of Global Climate Change

According to the World Economic Forum’s Global Risks Report 2021, the failure to mitigate and adapt to climate change is “the most impactful” risk facing communities worldwide—ahead of even weapons of mass destruction and water crises. Blame its cascading effects: As climate change transforms global ecosystems, it affects everything from the places we live to the water we drink to the air we breathe.

And though climate change affects everyone in some way, it’s indisputable that its most negative impacts are borne disproportionately by certain groups: women, children, people of color, Indigenous communities, and the economically marginalized. Climate is a human rights issue.

Extreme weather

As the earth’s atmosphere heats up, it collects, retains, and drops more water, changing weather patterns and making wet areas wetter and dry areas drier. Higher temperatures worsen and increase the frequency of many types of disasters, including storms, floods, heat waves, and droughts. These events can have devastating and costly consequences, jeopardizing access to clean drinking water, fueling out-of-control wildfires, damaging property, creating hazardous-material spills, polluting the air, and leading to loss of life.

Dirty air

Air pollution and climate change are inextricably linked, with one exacerbating the other. When the earth’s temperatures rise, not only does our air get dirtier—with smog and soot levels rising accordingly—but it also becomes filled with more allergenic pollutants, such as circulating mold (thanks to damp conditions from extreme weather and more floods) and pollen (due to longer, stronger pollen seasons).

Health risks

According to the World Health Organization, “climate change is expected to cause approximately 250,000 additional deaths per year” between 2030 and 2050. As global temperatures rise, so do the number of fatalities and illnesses from heat stress, heatstroke, and cardiovascular and kidney disease. And as air pollution worsens, so does respiratory health—particularly for the 300 million people living with asthma worldwide; there’s more airborne pollen and mold to torment hay fever and allergy sufferers too. Extreme weather events, such as severe storms and flooding, can lead to injury, drinking water contamination, and storm damage that may compromise basic infrastructure or lead to community displacement. Indeed, historical models suggest the likelihood of being displaced by a disaster is now 60 percent higher than it was four decades ago—and the largest increases in displacement are being driven by weather- and climate-related events. (It’s worth noting that displacement comes with its own health threats, such as increases in urban crowding, trauma, social unrest, lack of clean water, and transmission of infectious diseases.) A warmer, wetter world is also a boon for insect-borne diseases such as dengue fever, West Nile virus, and Lyme disease.

Rising seas

The Arctic is heating up twice as fast as any other place on the planet. As its ice sheets melt into the seas, our oceans are on track to rise by anywhere from 0.95 to 3.61 feet by the end of this century, threatening coastal ecosystems and low-lying areas. Island nations face particular risk, as do some of the world’s largest cities, including New York City, Miami, Mumbai in India, and Sydney in Australia.

Warmer, more acidic oceans

The earth’s oceans absorb between one-quarter and one-third of our fossil fuel emissions and are now 30 percent more acidic than they were in preindustrial times. This acidification poses a serious threat to underwater life, particularly creatures with calcified shells or skeletons like oysters, clams, and coral. It can have a devastating impact on shellfisheries, as well as the fish, birds, and mammals that depend on shellfish for sustenance. In coastal communities where fishing and seafood production sustain the local economy, this impact extends to human populations as well, destroying livelihoods and opening the door to economic ruin. Rising ocean temperatures are also altering the range and population of underwater species and contributing to coral bleaching events that are capable of killing entire reefs—ecosystems that support more than 25 percent of all marine life.