Is 2018 destined to be the warmest year in modern history? It’s hard to argue against such a claim when facts state that 16 out of the 17 of the hottest years on record have occurred since the turn of the 21st century. Yes, anthropogenic global warming is real and is happening right now; a direct result of human activities (burning of fossil fuels, deforestation, etc…) that have increased greenhouse gas concentrations in the atmosphere.
Earth’s mean temperature has overall increased by 0.8°C since the beginning of the 20th century, ensuing a reduction in polar ice caps, a rise in sea level, and visible changes in rainfall and weather patterns across the globe. Such abrupt change in climate has already impacted our much valued ecosystem and biodiversity. Earth’s climate has often undergone massive transformation over a span of millennia in its history, but the current change is quite rapid and influencing the adaptability of numerous vulnerable plant and animal species who finds it difficult to adjust to the new regime in a short period of time.
With the highest rate of warming anywhere on the planet, global warming is largely affecting the Arctic ecosystem. The extent of floating sea ice in the region has drastically reduced over the past forty years, risking the habitat of polar bears, puffins, and other arctic creatures that depend on it for survival. The algae that grows underside the Arctic ice is responsible for a quarter of the ocean’s primary production, and its depletion can disrupt the food chain by affecting fishes, birds, and mammals in the region. The heating of the surface air in the Arctic has also resulted in the loss of Tundra vegetation crucial to the survival of several local species.
Encompassing around 70% of the earth’s surface, the effect of global warming on our ocean ecosystems has been more pronounced. With a rise in sea surface temperature, changes in ocean current circulation, and an increase in ocean acidification – oceans are reaching conditions not observed for millions of years. Rising sea surface temperature has been linked to the global decline of phytoplankton productivity, microscopic ocean plants that use photosynthesis to convert atmospheric carbon dioxide into oxygen. It is estimated that phytoplanktons supply more than half of the oxygen that we breathe, and its decline can have severe repercussions not only in marine ecosystems but also for humans. With more carbon dioxide getting dissolved in the oceans, the acidic water inhibits a chemical process called calcification; thinning the exoskeletons and shells of several crustaceans and molluscs vital in the marine food chain. Ocean acidification has also resulted in the bleaching of coral reefs, which account for a third of marine biodiversity, around the world. The occurrence of oceanic dead zones (areas of less or no oxygen) are also now appearing across the globe – leading to the decline in coastal plants and forests, esp. mangroves.
On land surfaces, rapid warming and deforestation has gradually shifted the physical range of several species; with more cold blooded animals migrating towards higher latitudes and altitudes. Many species of lizards, currently living at the edge of their “thermal limits”, have either migrated to colder regions or has become extinct. Countries in Europe like Denmark and Norway have seen the invasion of pests like Colorado pine beetles, with temperatures warm enough to sustain their population. Such invasion disrupts the local ecosystem by effecting the food chain. Warm temperatures increase the spread of such pests, with fungi like the wheat rust and insects like the mountain pine beetle shifting their distribution away from the equator towards poles. Studies estimate that with global warming, more crops will be lost to the outbreak of such pests – affecting our food production and local ecosystem. With more urbanization and deforestation, pollinators like bees, ladybugs, and beetles have also seen a decline in their population due to change in habitat. Global warming has also lead to changes in the timing of seasonal life cycle events – causing a decoupling in predator-prey relationships and disrupting the ecosystem.
Healthy ecosystems and rich diversity are paramount factors to sustain life on Earth. All across the globe, we have been observing a change in our biodiversity which impacts several of our ecosystems. Although the Paris Agreement has vowed to keep the rise in temperature within 1.6°C by the end of the century, the IPCC reports that the projected increase of 2-3°C will result in 20-30% of our current species being at extremely dangerous risk of becoming extinct. At the current rate of warming, scientists have predicted that 90% of coral reefs may bleach by 2050. On the other hand, ice free summers in the Arctic could not only lead to the extinction of polar bears but also the entire Arctic biome. We have always been part of a delicate ecosystem, with complex interactions among and between species and their habitats. Global warming causes such interactions to change, with species failing to adapt to the sudden change in climate caused by us.