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  • Climate change: How do we know it is happening and caused by humans?

The climate is the average weather in a place over many years. Climate change is a shift in those average conditions. But scientists say that there is no doubt that humans cause the remarkably rapid climate change seen over the past century. In particular, they say it is due to the widespread use of fossil fuels – coal, oil, and gas – in homes, factories, and transport. When fossil fuels burn, they release greenhouse gases – primarily carbon dioxide (CO2). These gases trap the Sun’s heat in the atmosphere, causing the planet’s temperature to rise.

The average temperature at the Earth’s surface has risen about 1.1C since 1850. Furthermore, each of the last four decades has been warmer than any that preceded it, since the middle of the 19th Century.

These conclusions come from analyses of millions of measurements gathered in different parts of the world. The temperature readings are collected by weather stations on land, on ships, and by satellites.

What are the effects of climate change so far?

Climate change has already had a range of effects on various aspects of the environment, societies, and economies. While the specific impacts can vary across regions, some common effects of climate change observed so far include:

  1. Rising temperatures: Global average temperatures have been increasing, resulting in heatwaves and more frequent and intense hot weather events. This can lead to heat-related illnesses, heat stress, and reduced agricultural productivity.
  2. Changing precipitation patterns: Climate change has altered rainfall patterns, resulting in more frequent and intense rainfall in some areas and prolonged droughts in others. This can lead to increased risks of flooding, water scarcity, crop failure, and impacts on freshwater availability.
  3. Sea-level rise: Warmer temperatures have caused glaciers and ice caps to melt, leading to rising sea levels. This poses risks to coastal areas, increasing the vulnerability of low-lying regions to storm surges, erosion, and saltwater intrusion into freshwater sources.
  4. Ocean acidification: Increased carbon dioxide emissions have led to the acidification of oceans. This has adverse effects on marine ecosystems, including coral bleaching, reduced shellfish populations, and disruption of the marine food chain.
  5. Extreme weather events: Climate change has contributed to more frequent and intense extreme weather events, such as hurricanes, cyclones, droughts, wildfires, and heavy precipitation events. These events can result in significant property damage, loss of lives, displacement of communities, and disruptions to infrastructure and economies.
  6. Health impacts: Climate change has implications for human health. Increased heatwaves can lead to heat-related illnesses and deaths. Changes in temperature and precipitation patterns can affect the spread of infectious diseases and impact food and waterborne diseases.
  7. Economic consequences: Climate change can have significant economic impacts. Extreme weather events can cause extensive damage to infrastructure, agriculture, and property, leading to increased costs for recovery and reconstruction. Disruptions to agricultural productivity, water availability, and tourism can also affect economies.

People living in developing countries are expected to suffer the most as they have fewer resources to adapt.

What are governments doing about climate change?

In a landmark agreement signed in Paris in 2015, almost 200 countries pledged to try to keep global warming to 1.5C.

To achieve this, scientists said that countries should achieve net zero CO2 emissions by 2050. Net zero means reducing greenhouse gas emissions as much as possible and removing any remaining emissions from the atmosphere.

Most countries have, or are considering, net zero targets, but many of these are dated after 2050.

Real-world action has been slow, and the levels of greenhouse gases in the atmosphere are still rising.

By Asif Raza

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