Small shifts have big consequences- Climate Change
Climate change has been accumulating slowly but relentlessly for decades. The changes might sound small when you hear about them – another tenth of a degree warmer, another centimeter of sea level rise – but seemingly small changes can have big effects on the world around us, especially regionally.
The problem is that while effects are small at any time, they accumulate. Those effects have now accumulated to the point where their influence is contributing to damaging heat waves, drought and rainfall extremes that can’t be ignored.
The most recent report from the United Nations’ Intergovernmental Panel on Climate Change is more emphatic than ever: Climate change, caused by human activities like burning fossil fuels, is having damaging effects on the climate as we know it, and those effects are rapidly getting worse.
Earth’s energy imbalance
An excellent example of how climate change accumulates is Earth’s energy imbalance. I am a climate scientist and have a new book on this about to be published by Cambridge University Press.
The Sun bombards Earth with a constant stream of about 173,600 terawatts (that is 12 zeros) of energy in the form of solar radiation. About 30% of that energy is reflected back into space by clouds and reflective surfaces, like ice and snow, leaving 122,100 terawatts to drive all the weather and climate systems around us, including the water cycle. Almost all of that energy cycles back to space – except for about 460 TW.
That remaining 460 TW is the problem we’re facing. That excess energy, trapped by greenhouse gases in the atmosphere, is heating up the planet. That is the Earth’s energy imbalance, or in other words, global warming.
July 2021 was Earth’s hottest month on record and was marked by disasters, including extreme storms, floods and wildfires
Consequences of more heat
Over oceans, the extra heat provides a tremendous resource of moisture for the atmosphere. That becomes latent heat in storms that supersizes hurricanes and rainstorms, leading to flooding, as people in many parts of the world have experienced in recent months.
Air can contain about 4% more moisture for every 1 degree Fahrenheit (0.55 Celsius) increase in temperature, and air above the oceans is some 5% to 15% moister than it was prior to 1970. Hence, about a 10% increase in heavy rain results as storms gather the excess moisture.
Again, this may not sound like much, but that increase enlivens the updrafts and the storms, and then the storm lasts longer, so suddenly there is a 30% increase in the rainfall, as has been documented in several cases of major flooding.
In Mediterranean climates, characterized by long, dry summers, such as in California, eastern Australia and around the Mediterranean, the wildfire risk grows, and fires can be readily triggered by natural sources, like dry lightning, or human causes.
Extreme events in weather have always occurred, but human influences are now pushing them outside their previous limits.
The straw that breaks the camel’s back syndrome
So, while all weather events are driven by natural influences, the impacts are greatly magnified by human-induced climate change. Hurricanes cross thresholds, levees break and floods run amok. Elsewhere, fires burn out of control, things break and people die.
I call it “The straw that breaks the camel’s back syndrome.” This is extreme nonlinearity, meaning the risks aren’t rising in a straight line – they’re rising much faster, and it confounds economists who have greatly underestimated the costs of human-induced climate change.
The result has been far too little action both in slowing and stopping the problems, and in planning for impacts and building resilience – despite years of warnings from scientists. The lack of adequate planning means we all suffer the consequences.