What Is Global Warming?
Global warming is an alarming phenomenon which is characterized by a drastic increase in the average global temperature in the Earth’s atmosphere. Studies show that since 1950, the average Earth’s temperature has risen at the fastest rate in recorded history. The current temperature rise of approximately 1°C is detrimental and encompasses extreme weather events, rising sea levels, melting ice sheets, shifting habitats, and epidemic risks. Note that global temperature records are an estimate across the entire surface of the planet. In fact, the average global temperature is a function of the amount of energy received from the Sun and then radiated by the Earth, which depends largely on the chemical composition of the atmosphere and the levels of heat-trapping greenhouse gases.
The current global temperature rise of 1°C may reach 2°C, putting people, wildlife, and nature at risk. A UN report released by the Intergovernmental Panel on Climate Change (IPCC) warns that if authorities fail to keep global warming at 1.5°C above preindustrial era levels, drastic climate change effects will occur by 2040. In order to avert global warming, rapid solutions on individual, national, and international levels are required – with science playing a crucial role in the process.
Is Global Warming Real?
Although the global significance of the climate changes happening right now is eminent, global warming has become a hot topic marked by skepticism and controversy. Interestingly, climate change denial that contradicts scientific evidence is a common phenomenon, with high prevalence across the US. In a 23-country survey conducted by the YouGov-Cambridge Globalism Project, Indonesia (18%), Saudi Arabia (16%), and the US (13%) revealed the highest percentage of manmade climate deniers.
In the US alone, 13% of respondents said global warming is real, but human activity is not responsible, while 5% denied global warming is happening. Demographics influence climate change denial, with white Americans over 55 years revealing high levels of denial. Political views and the media are also major factors shaping people’s opinions; 52% of Republicans in the US, for instance, are more likely to ignore global warming. Interestingly, more than 56% of elected Republicans also deny the science behind global warming. We should note that President Trump was one of the main political figures fueling the climate-related conspiracies, claiming that global warming was a hoax fabricated by China and the UN 2015 Paris Climate Agreement a tactic to undermine the US economy.
Scientific Evidence for Global Warming
Despite all the controversy and political interests, the science behind global warming is clear: global warming is a fact. Satellite and laboratory data show that the trapping of carbon dioxide and other pollutants in the atmosphere causes the Earth to warm. With more than thousands of weather stations around the world, buoy-based measurements and Antarctic research, scientists show that climate change in response to CO2 and aerosols is imminent. Additionally, ancient evidence found in tree rings, glacial ice, coral reefs, and sedimentary rocks shows that the current warming is 10 times faster than the average rate of ice-age-recovery warming. In fact, proxy-based temperature variations reveal that today’s surface temperature changes are anomalous for the past 1,300-1,700 years (Mann et al., 2008). Scientific evidence shows that the Earth’s climate is changing due to the greenhouse effect and various manmade causes of pollution, resulting in landslides, flooding, and shifting of populations:
- Global temperatures are increasing: The average global temperature has increased with more than 0.9°C over the past century, with significantly higher rates over the last 35 years. In the US, in particular, the five warmest years on record took place in the last decade, with 2018 being the fourth warmest year on record. Note that global warming varies across land masses and water basins and is more significant over land due to the thermal inertia of the oceans. Rising global temperatures are challenging ecosystems and economies and putting ecological integrity and resilience at risk (GISTEMP Team, 2019, Hansen et al., 2010).
- Oceans are changing, and habitats are shifting: The ocean temperature has increased significantly since 1969, particularly in the top 700 meters. Additionally, increased global temperatures cause oxygen levels and nutrients in the oceans to decrease. Analyses of direct measurements at sites show that zones with minimum oxygen levels have increased by several million square kilometers during the past 50 years (Breitburg et al., 2018). These changes are challenging numerous species and habitats, such as the Adelie penguins in Antarctica (Clucas et al., 2014), as well as coral reefs worldwide.
- Sea levels are rising: The sea level is rising each year, with a record high in 2017 (Blunden, Arndt & Hartfield, 2017). Global sea levels are rising with approximately 0.3 cm each year and are expected to rise between 25.4 cm and 81.28 cm by the end of the century, putting numerous countries such as the Maldives at risk. To be more precise, satellite altimetry estimates that global sea levels have been increasing at a rate of ∼3 ± 0.4 mm per year since 1993. Research shows this rate is accelerating, and global sea levels may reach up to 65 cm by 2100 (Nerem et al., 2018).
- Ocean acidification is increasing: The acidity of the ocean waters has increased by 30% and the amount of carbon dioxide absorbed by 2 billion tons per year. Acidification affects coral skeletons, which are also prone to coral bleaching and extinction. Research shows that lower pH leads to a decline of 52-73% in the larval settlement on reefs.
- Corals are disappearing: In fact, coral bleaching is one of the clearest evidence that global warming is affecting species worldwide. A study showed that after the marine heat wave in 2016, the corals on the Great Barrier Reef started to accumulate excessive heat and suffered a tremendous die-off (Hughes et al., 2018).
- Ice sheets are melting: The ice sheets are melting at a high rate, contributing to sea-level rise. According to NASA’s Gravity Recovery and Climate Experiment, between 1993 and 2016, Antarctica has lost more than 127 billion tons of ice per year, while Greenland more than 286 billion tons per year. Consequently, sea level rise rates have tripled over the last ten years due to the melting of the Antarctic ice (IMBIE, 2018).
- Glaciers are disappearing: Glaciers – which contain ¾ of the world’s freshwater – are retreating worldwide, including in the Alps and the Himalayas. In Montana’s Glacier National Park, for instance, the number of glaciers has declined from 150 to 25. In addition, data provided by the U.S. Geological Survey and Portland State University shows that a large number of glaciers have shrunk since 1966.
- Snow and permafrost are melting: Snow is melting earlier, and spring snow has decreased over the past 50 years, particularly in the Northern Hemisphere. As the winter season shortens, whole regions are exposed at risk. In Yamal, Russia, for instance, as the permafrost started to melt in 2013, warm temperatures brought rain which then froze, leaving thousands of animals to starve. Sea ice is also melting earlier, which can be detrimental. A study showed that the earlier melting of Arctic sea ice in spring might lea