What’s the deal with global warming and climate change?

Our hearing is our alarm system.  When we perceive something dangerous or wonderful, hearing prompts attention and our brains work like noise-suppressing headphones. We begin to listen, focusing actively and tuning out sights and sounds that are unimportant.

Our Earth is warming.  The average temperature of the atmosphere and oceans has increased over the last century, melting snow and ice, well beyond the more natural warming that occurred during the medieval warm period in Europe that lasted from about AD 950 to 1250. While Europe warmed, there is little evidence that the rest of the world did. Therefore, many scientists call this period the medieval climatic anomaly. Today’s warming is global in scope.

In 1896, the Swedish Nobelist Svante Arrhenius predicted that burning fossil fuels adds carbon dioxide added to our Earth’s atmosphere, which would raise the average global temperature. At that time, 120 years ago, many scientists argued against this theory, believing that humanity was too small to impact complex and expansive climate cycles.

Driven by the Cold War in the 1950’s, military agencies required more accurate predictions about the global weather and the state of the seas. By the end of the decade, military funded research convinced scientists that greenhouse gases were increasing in the atmosphere.

Why do greenhouse gases contribute to global warming? The heat that the Earth receives from the Sun is either absorbed by the atmosphere or oceans, or reflected back into the solar system and universe. Greenhouse gases absorb far more heat than the major constituents of our atmosphere, which are nitrogen and oxygen. Thus, more heat is retained in the atmosphere and then transferred to the oceans, and less reflected away from the Earth.

Carbon dioxide is a greenhouse gas.  Its presence in our the atmosphere is increasing as we burn coal and natural gas to produce electricity, and use gasoline to power transportation.  Hence, the warming atmosphere is transferring more heat to our Earth’s seas and oceans, and melting glaciers.

Our Earth’s oceans have a major influence on climate. They behave as a massive solar panel by absorbing the bulk of the Sun’s radiated heat. Oceans do not just store heat, they also distribute it across our planet through ocean currents and as water is evaporated into rain and storms that are carried over thousands of kilometres.

Ocean currents are the conveyor belts that transport warm water and precipitation from the equator to the poles in the form of rain and snow, clockwise in the northern hemisphere and anticlockwise in its southern counterpart. Since the Sun’s radiation is uneven across our Earth, these currents help to even out global temperatures. If this conveyor belt that brings heat from the equator did not exist, Canada would be even colder in the winter and equatorial regions warmer.

To recapitulate, the more greenhouse gases there are in the atmosphere, the warmer it becomes by trapping more of the Sun’s heat.  It transfers that additional warmth to the oceans which, driven by wind currents, circulate and distribute the heat through ocean currents and precipitation, thus shaping local weather conditions and the global climate.

Despite understanding this straightforward physics clearly, science has not progressed far enough to state the exact influence of global warming on climate change with certainty. We cannot yet predict how yesterday’s warming of the atmosphere above Paris will influence tomorrow’s weather in Vancouver.

Although climate science is not fully certain, it isn’t wrong.  There is a clear logic behind the reasons for global warming and climate change. However, many of us do not listen to what the eventual impact will be. Our alarm system has broken down. To repair it, we must participate in the discussion about global climate change with our noise-suppressing headphones on.

Climate change can be swift and relentless. Let’s move the needle rapidly through environmental, economic and social solutions for sustainability.

(Recommended reading: The Discovery of Global Warming by Spencer Weart.)


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