Climate change is a significant, long-term shift in weather patterns that can refer to one place or the planet as a whole.
While 'weather' is what we experience when we step outside at any given moment – including the temperature, precipitation, and humidity we feel on a daily basis – 'climate' refers to these patterns over three decades or more. This is why some places described as having a tropical climate can experience days without rain, while others described as arid can have occasional showers.
These, in turn, can affect energy in the system, altering air and water currents, precipitation, ground moisture, and the prevalence of various species.
What's special about climate change today?
Today, as a consequence of humans emitting heat-trapping gases into the atmosphere, global climate changes have become so extreme and widespread that the impact is collectively referred to as a climate crisis.
Not only has this caused an unprecedented increase in the planet's average temperature, it has already led to extreme polar and glacial ice melt, rising sea levels, widespread reductions in biodiversity, and changes in extreme weather events like fires, flooding, storms and heat waves.
The overwhelming consensus on the primary cause of this particular period of warming is a large-scale addition of greenhouse gases. Most of these are the direct result of human activity over the past two centuries, namely the combustion of fossil fuels such as oil, gas, and coal in transport and industry.
Compared with the average global temperature a century or two ago, our current temperature is already warmer by a touch over 1 degree Celsius. What will happen in the future depends largely on our greenhouse gas emissions going forward.
The Intergovernmental Panel on Climate Change (IPCC) currently recommends limiting global temperatures to 1.5 degrees Celsius, while the Paris Agreement aims to keep global temperatures below 2°C. Or else, we might reach a point of no return.
Going above those thresholds could cause a global cascade of events outside of our control, scientists warn. These are known as tipping points, and their natural feedback systems might cause heat to accumulate even faster in the atmosphere, leading to a bleak future scenario known as the "Hothouse Earth".
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