Is Climate Change a Threat to Humanity?

A review of the evidence.

The planet has been warming just over 1 degree C over the last 150 years and Climate Models show further projected rises. Scientists accept that CO2 and Methane are greenhouse gases, though some do question as to the degree of natural variability involved in this rise. Do human emissions of greenhouse gases represent a threat to humanity?

Distribution of excess CO2 and Warming

While you might think that excess CO2 is dispersed evenly around the globe NASA satellites shows that actually this tends to be concentrated around the Northern Hemisphere with peaks in winter, falling in summer:

If excessive CO2 levels stay in the Northern Hemisphere what about excess warming? Again, the 2022 IPCC report shows this mostly contained to the Northern Hemisphere and again mostly in winter. Note the average temperature rise is 1 degree Celsius. This leaves the tropics barely affected and questions the need to to further limit changes. Is an average January temperature in Alaska of -12 degrees Celsius instead of -15 degrees Celsius really such a problem?

Note that this pattern of warming is also correlated with satellite temperature measurements available on Dr Roy Spencer's website where the excess warming is again concentrated in the northern hemisphere with limited to no warming in the tropics.

Tropical Storm Trends

Given that the tropics are not showing large increases in temperatures it is unsurprising that the trends in Trends in Global Cyclone Activity are down. (due to more Pacific cooling La Nina events):

Fewer hurricanes is obviously a good thing. At some stage though there will be a big one, though it will need to be bad to match the Great Hurricane of 1780

Global Greening

Despite rising, CO2 levels are still low, having increased from 0.03% to just over 0.04% (i.e. still only 1 part in 2500). Plants require CO2 for photosynthesis, so is this increase good for plant growth? Indeed this is what NASA has found:

“…a quarter to half of Earth’s vegetated lands has shown significant greening over the last 35 years largely due to rising levels of atmospheric carbon dioxide, and that this greening is helping reduce climate impacts of elevated CO2 levels.”

NASA graphic showing Global Greening.

Global Agricultural Output

If the planet is greening what about global agricultural output? The world’s farmers are obviously supremely adaptable as output has grown year on year (due to modern farming techniques , fertilizer produced from Gas, but increased CO2 will have helped a little). If warming leads to further temperature rises with extended growing seasons in the Northern Hemisphere then we should expect this trend to continue.

Even tropical crops which may have expected to be impacted by increased temperatures such as Cocoa and Coffee have shown long-term trend increases. Be very wary of any government attempting to restrict or ban synthetic fertilizer like Sri Lanka

Sea Level Rise

In a warming planet the seas are rising. Does this constitute a threat to those in low-lying Islands such as the Maldives? Apparently not according to this study which showed

“a large increase the area of atoll islands, with 61.74 km² of land added between 2000 and 2017, results show that most changes in atoll land area have taken place in the Maldivian archipelago and on atolls in the South China Sea.”

Even low-lying Bangladesh is gaining on average 20 square KM per year from sediment accumulation.

Sea levels (according to NASA) are currently rising at about 3 mm per year, or 30 cm in about 100 years time. It remains to be seen whether this rate of rise will ever constitute a serious threat to any nation.

Forest Fires

Extremely evocative: “the planet is literally burning” forest fires are an inevitable occurrence in hot, dry areas, especially when it appears most are started by people. But are these increasing? If we look at the US it appears not. Preventing large-scale forest fires requires a lot of maintenance in building fire-breaks etc. Having fossil fuel powered machinery helps with this.

US Forest Fires

Floods

Floods are a combination of extreme weather events (heavy, slow-moving clouds) and also landscape. As areas become built up and tree cover diminished they become liable to flooding. The 2022 Pakistan floods are being ascribed to climate change (even though Pakistan regularly floods during the Monsoon season). It should be noted that tree cover in Pakistan is very low at 3% and that population growth from 40 million in 1950 to over 200 million today gives an indication of how much more built up it is.

Droughts

The headlines say these are increasing, but what does the actual data say?

This comprehensive review by the Royal Society looked at the standardized precipitation index (SPI) i.e. amount of rain and found that this was increasing:

“…..Figure 1 shows a predominance of positive and significant SPI trends in the 12-month SPI (January–December) for the period 1900–2020. Only a few regions showed a dominant decreasing significant trend (southwestern Australia, southern South Africa and Central Europe) informative of drying conditions….

and that

“..In the vast majority of the world, trends in meteorological drought duration and magnitude are not statistically significant, with the exception of some small regions of Africa and South America…”

Water scarcity is becoming more of an issue due to population growth. Ultimately though the continued increases in Agricultural Production and indeed global greening from increased CO2 levels suggest that this is not a significant threat to humanity.

Heat vs Cold Deaths

Repeated studies have shown that deaths from cold far exceed those from heat (generally around 9 times as large).

Methane

Methane constitutes 0.00018% of the atmosphere and is estimated to contributed 30% of the rise in global temperatures (so about 0.3 degrees). But it only lasts 12 only years in the Atmosphere, so would requires an ever-increasing amount of emissions to make a further significant difference. There is also the question as to why global methane levels flatlined in the early part of the 2000’s despite rising numbers of ruminants. In addition if we are to move away from finite fossil fuels then we would need to replace natural gas fertilizer with animal fertilizer. Attempts by politicians to reduce agricultural methane emissions (from ruminants or even rice production), which at best will put food prices up, and at worst threaten food security, should be strongly resisted.

Cows are not a Climate Problem.

Warming as an Insurance Policy?

Historically severe volcanic eruptions which cool the planet have happened every few hundred years or so - a list is here and these are thought to be the most likely cause of the Little Ice Age. We may also experience a Maunder Minimum period of almost no sunspots at all, which

“led to reduction of solar irradiance by 0.22% from the modern one and a decrease of the average terrestrial temperature by 1.0–1.5°C.”

If and when such events occur again we would be most likely very grateful for any CO2 and Methane warming effects.

Conclusion and thoughts on Net Zero

So it appears that the risks of Climate Change have been overstated and the benefits understated (or rather ignored) by the media. So why the push to Net Zero? I believe the reason is to do with finite fossil fuels. Despite an increase from fracking in the US there is no doubt that eventually global oil and gas production will decrease (the UK where I live, peaked in 1998). Global demand is outstripping supply leading to sharply rising energy (and food) prices. So it would make sense to get the population to willingly cut down their usage. Of course those in charge would still rather have their Private Jets (which are now exempt from fuel duty in the EU) to jet to Marbella and St Tropez, with the rest of us unable to afford to join them.

But whatever those in the west do you should know that the Chinese (and India) have decided that CO2 induced Climate Change doesn't pose a threat to them: