Amidst the clamor for urgent action to supposedly combat climate change, the scientific and engineering realities of such action are usually overlooked. Let’s imagine for a moment that we humans are indeed to blame for global warming and that catastrophe is imminent without drastic measures to curb fossil fuel emissions – views not shared by climate skeptics like myself.

In this and the subsequent blog post, I’ll show how proposed mitigation measures are either impractical or futile. We’ll start with the 2015 Paris Agreement – the international agreement on cutting greenhouse gas emissions, which 195 nations, together with many of the world’s scientific societies and national academies, have signed on to.

The agreement endorses the assertion that global warming comes largely from our emissions of greenhouse gases, and commits its signatories to “holding the increase in the global average temperature to well below 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels,” preferably limiting the increase to only 1.5 degrees Celsius (2.7 degrees Fahrenheit). According to NASA, current warming is close to 1 degree Celsius (1.8 degrees Fahrenheit).

How realistic are these goals? To achieve them, the Paris Agreement requires nations to declare a voluntary “nationally determined contribution” toward emissions reduction. However, it has been estimated by researchers at MIT (Massachusetts Institute of Technology) that, even if all countries were to follow through with their voluntary contributions, the actual mitigation of global warming by 2100 would be at most only about 0.2 degrees Celsius (0.4 degrees Fahrenheit).

Higher estimates, ranging up to 0.6 degrees Celsius (1.1 degrees Fahrenheit), assume that countries boost their initial voluntary emissions targets in the future. The agreement actually stipulates that countries should submit increasingly ambitious targets every five years, to help attain its long-term temperature goals. But the targets are still voluntary, with no enforcement mechanism.

Given that most countries are already falling behind their initial pledges, mitigation of more than 0.2 degrees Celsius (0.4 degrees Fahrenheit) by 2100 seems highly unlikely. Is it worth squandering the trillions of dollars necessary to achieve such a meager gain, even if the notion that we can control the earth’s thermostat is true?

Another reality check is the limitations of renewable energy sources, which will be essential to our future if the world is to wean itself off fossil fuels that today supply almost 80% of our energy needs. The primary renewable technologies are wind and solar photovoltaics. But despite all the hype, wind and solar are not yet cost competitive with cheaper coal, oil and gas in most countries, when subsidies are ignored. Higher energy costs can strangle a country’s economy.