GLOBAL WARMING

Global warming, the gradual heating of Earth’s surface, oceans and atmosphere, is caused by human activity, primarily the burning of fossil fuels that pump carbon dioxide (CO2), methane and other greenhouse gases into the atmosphere.

Increase in average temperatures and temperature extremes

One of the most immediate and obvious effects of global warming is the increase in temperatures around the world. The average global temperature has increased by about 1.4 degrees Fahrenheit (0.8 degrees Celsius) over the past 100 years, according to the National Oceanic and Atmospheric Administration

Since record keeping began in 1895, the hottest year on record worldwide was 2016, according to NOAA and NASA data. That year Earth’s surface temperature was 1.78 degrees F (0.99 degrees C) warmer than the average across the entire 20th century. Before 2016, 2015 was the warmest year on record, globally. And before 2015? Yep, 2014. In fact, 16 of the 17 warmest years on record have happened since 2001, according to NASA.

For the contiguous United States and Alaska, 2016 was the second-warmest year on record and the 20th consecutive year that the annual average surface temperature exceeded the 122-year average since record keeping began,according to NOAA.

Extreme weather events

Global warming may also lead to extreme weather other than cold or heat extremes. For example, hurricane formations will change. Though this is still a subject of active scientific research, current computer models of the atmosphere indicate that hurricanes are more likely to become less frequent on a global basis, though the hurricanes that do form may be more intense.

“And even if they become less frequent globally, hurricanes could still become more frequent in some particular areas,” said atmospheric scientist Adam Sobel, author of “Storm Surge: Hurricane Sandy, Our Changing Climate, and Extreme Weather of the Past and Future” (HarperWave, 2014).

“Additionally, scientists are confident that hurricanes will become more intense due to climate change.” This is because hurricanes get their energy from the temperature difference between the warm tropical ocean and the cold upper atmosphere. Global warming increases that temperature difference.

Scientists project that extreme weather events, such as heat waves, droughts, blizzards and rainstorms will continue to occur more often and with greater intensity due to global warming, according to Climate Central. Climate models forecast that global warming will cause climate patterns worldwide to experience significant changes. These changes will likely include major shifts in wind patterns, annual precipitation and seasonal temperatures variations.

Ice melt

One of the primary manifestations of climate change so far is melt. North America, Europe and Asia have all seen a trend toward less snow cover between 1960 and 2015, according to 2016 research published in the journal Current Climate Change Reports. According to the National Snow and Ice Data Center, there is now 10 percent less permafrost, or permanently frozen ground, in the Northern Hemisphere than there was in the early 1900s. The thawing of permafrost can cause landslides and other sudden land collapses. It can also release long-buried microbes, as in a 2016 case when a cache of buried reindeer carcasses thawed and caused an outbreak of anthrax.

Glacial retreat, too, is an obvious effect of global warming. Only 25 glaciers bigger than 25 acres are now found in Montana’s Glacier National Park, where about 150 glaciers were once found, according to the U.S. Geological Survey. A similar trend is seen in glacial areas worldwide. According to a 2016 study in the journal Nature Geoscience, there is a 99 percent likelihood that this rapid retreat is due to human-caused climate change. Some glaciers retreated up to 15 times as much as they would have without global warming, those researchers found.

Sea levels and ocean acidification

In general, as ice melts, sea levels rise. In 2014, the World Meteorological Organization reported that sea-level rise accelerated 0.12 inches (3 millimeters) per year on average worldwide. This is around double the average annual rise of 0.07 in. (1.6 mm) in the 20th century.

Melting polar ice in the Arctic and Antarctic regions, coupled with melting ice sheets and glaciers across Greenland, North America, South America, Europe and Asia, are expected to raise sea levels significantly. And humans are mostly to blame: In the IPCC report released on Sept. 27, 2013, climate scientists said they are at least 95 percent certain that humans are to blame for warming oceans, rapidly melting ice and rising sea levels, changes that have been observed since the 1950s.

Plants and animals

The effects of global warming on the Earth’s ecosystems are expected to be profound and widespread. Many species of plants and animals are already moving their range northward or to higher altitudes as a result of warming temperatures, according to a report from the National Academy of Sciences.

Additionally, migratory birds and insects are now arriving in their summer feeding and nesting grounds several days or weeks earlier than they did in the 20th century, according to the EPA.

Warmer temperatures will also expand the range of many disease-causing pathogens that were once confined to tropical and subtropical areas, killing off plant and animal species that formerly were protected from disease.

These and other effects of global warming, if left unchecked, will likely contribute to the disappearance of up to one-half of Earth’s plants and one-third of animals from their current range by 2080, according to a 2013 report in the journal Nature Climate Change.

Social effects

As dramatic as the effects of climate change are expected to be on the natural world, the projected changes to human society may be even more devastating.

Agricultural systems will likely be dealt a crippling blow. Though growing seasons in some areas will expand, the combined impacts of drought, severe weather, lack of accumulated snowmelt, greater number and diversity of pests, lower groundwater tables and a loss of arable land could cause severe crop failures and livestock shortages worldwide.

North Carolina State University also notes that carbon dioxide is affecting plant growth. Though CO2 can increase the growth of plants, the plants may become less nutritious.

In addition to less nutritious food, the effect of global warming on human health is also expected to be serious. The American Medical Association has reported an increase in mosquito-borne diseases like malaria and dengue fever, as well as a rise in cases of chronic conditions like asthma, most likely as a direct result of global warming. The 2016 outbreak of Zika virus, a mosquito-borne illness, highlighted the dangers of climate change. The disease causes devastating birth defects in fetuses when pregnant women are infected, and climate change could make higher-latitude areas habitable for the mosquitos that spread the disease, experts said. Longer, hotter summers could also lead to the spread of tick-borne illnesses.

Additional resources:

• EPA: Climate Change: Basic Information

• NASA: Global Climate Change

• California Office of Planning & Research: List of worldwide scientific organizations that hold the position that climate change has been caused by human action

• https://www.livescience.com/37057-global-warming-effects.html

Sümeyye Var

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