Global Warming Spectical Arguments

 

Climates changed before:

Myth: Climate is always changing. We have had ice ages and warmer periods when alligators were found in Spitzbergen. Ice ages have occurred in a hundred thousand year cycle for the last 700 thousand years, and there have been previous periods that appear to have been warmer than the present despite CO2 levels being lower than they are now. More recently, we have had the medieval warm period and the little ice age.

Science: Scientific analysis of past climates shows that greenhouse gasses, principally CO2, have controlled most ancient climate changes. The evidence for that is spread throughout the geological record. This makes it clear that this time around humans are the cause, mainly by our CO2 emissions.

 

It's the sun:
Myth: "Over the past few hundred years, there has been a steady increase in the numbers of sunspots, at the time when the Earth has been getting warmer. The data suggests solar activity is influencing the global climate causing the world to get warmer."

Science: In the last 35 years of global warming, the sun has shown a slight cooling trend. Sun and climate have been going in opposite directions. In the past century, the Sun can explain some of the increase in global temperatures, but a relatively small amount.

 

It's not bad:
Myth: "Two thousand years of published human histories say that warm periods were good for people. It was the harsh, unstable Dark Ages and Little Ice Age that brought bigger storms, untimely frost, widespread famine and plagues of disease."

Science: The consequences of climate change become increasingly bad after each additional degree of warming, with the consequences of 2°C being quite damaging and the consequences of 4°C being potentially catastrophic.

 

Some adverse impacts are expected even before we reach the 2°C limit, such as hundreds of millions of people being subjected to increased water stress, increasing drought at mid-latitudes, increased coral bleaching, increased coastal damage from floods and storms, and increased morbidity and mortality from more frequent and intense heat waves, floods, and droughts. However, by and large these are impacts which we should be able to adapt to, at a cost, but without disastrous consequences.

Once we surpass the 2°C limit, the impacts listed above are exacerbated, and some new impacts will occur. Most corals will bleach, and widespread coral mortality is expected. Up to 30% of global species will be at risk for extinction, and the figure could exceed 40% if we surpass 4°C, as we continue on the path toward the Earth's sixth mass extinction. Coastal flooding will impact millions more people at ~2.5°C, and a number of adverse health effects are expected to continue rising along with temperatures.