The United Nations’ Intergovernmental Panel on Climate Change (IPCC) is unequivocal in its identification of the tight and close relationship between anthropogenic emissions of CO₂ and global warming; and from this spins forth a whole range of other climatic disruptions. Their graph in their latest summary for policymakers¹ – SPM 10 above – demonstrates the relationship between accumulating CO₂ and rising temperatures. Rapid growth, industrialisation, and the burning of fossil fuels, as outlined elsewhere in T10 (e.g. see Section 8, ‘Energy’) have rapidly increased the concentration of CO₂ and other greenhouse gases (e.g. methane – CH₄, and nitrous oxide – N₂O) in the atmosphere; the IPCC summarises the rise and concentrations thus:

“In 2019, atmospheric CO2 concentrations were higher than at any time in at least 2 million years (high confidence), and concentrations of CH4 and N2O were higher than at any time in at least 800,000 years (very high confidence). Since 1750, increases in CO2 (have been) (47%) and CH4 (156%)”…and “N2O (23%).” ^ibid.

To put this into perspective, humans have been around for only roughly two million years, so this is unprecedented – certainly in human terms. This exceptional, recent rise in the emission of greenhouse gases is far beyond earth’s capacity to absorb this ‘waste’, so much so that it now comprises 60% or more of the global footprint of humankind:

The above graph from the Global Footprint Network (GFN) divides our global footprint into contributions by land types (uses), and ‘carbon’ (dark blue), and converts all impacts to an area measure expressed as ‘number of earths’. It demonstrates clearly how far beyond sustainable or assimilative levels are our current carbon emissions, so this inevitably leads to build-up in the atmosphere, oceans, soils and lakes of the world, with major consequences for climate and life. The Global Footprint Network sums up the situation as:

“The carbon Footprint is currently 60 percent of humanity’s overall Ecological Footprint and its most rapidly growing component. Humanity’s carbon Footprint has increased 11-fold since 1961.”²

It is hard to believe an increase of 11-fold since 1961, but as we have seen so often in T10, the scale and impact of modern, terribly recent, humanity, is gobsmacking, such is its size, and as unprecedented as it is – almost – beyond comprehension.

The major contributors or contributions to global carbon pollution can be presented in various ways, but perhaps the most useful is via countries, or economic sector, or activity. Looking to countries first, the GFN presents the situation as: ^ibid.

The pie chart is an interesting mix of Developed and Developing Countries and impact is a consequence of high consumption, e.g. the USA; high population, e.g. China; or a mixture of both, e.g. the Russian Federation. The ‘big five’ are: China, USA, India, Russia, and Japan. A country’s economic structure, e.g. a strong manufacturing base, has an effect also.

Sorted another way, via economic sector, an earlier IPCC report (2014³) presented contributions as stemming primarily from electricity production, agriculture and forestry, and industry.

A third way to track the source of emissions is to look at activity types; an example is provided below for Greece and Athens from the GFN⁴, and although it is of total footprint, we can roughly assume that as much of this footprint will comprise carbon emissions, then the broad categories will hold. Food, Transport, Goods, and Infrastructure are the big factors in Greece, and if ‘Housing’ is added, then it is a good summation of the world picture.

The sources of greenhouse gas emissions and their quantity is clear, but their effects are extremely diffuse and not just confined to temperature increases. The IPCC’s latest report¹ attempts to summarise these impacts in its Figure SPM 9 – as follows:

For our purposes, ‘Climate Impact Drivers’ can be interpreted as ‘Climate Change Effects’ and the IPCC lists 35 effects, ranging from extreme heat, to fire weather, to snow avalanches, to ocean acidity. The vertical axis refers to the number of regions in the world affected, with above the line – purple – being an increase, and below the line – brown – a decrease. The changes that affect the most regions are:

• increased temperature
• extreme heat
• heavy precipitation/flood
• increased fire weather
• decreased cold spells and frost
• sea level rise
• increased coastal flooding
• increased coastal erosion
• increased marine heatwaves
• increased ocean acidity
• increased atmospheric CO₂
• increased snow /glacier/ice sheet melt

These will bend, and sometimes fracture, the framework of the natural world.

The impact of three of these broad changes – hot extremes, heavy precipitation, and agricultural and ecological drought – is presented for the regions of the world in the following map/diagram^ibid. where regions are represented as hexagons, e.g. ‘NZ’ at the bottom right is New Zealand. Data is lacking for a number of areas, but the picture, at least for heat, is clear: increase with high level of confidence in human cause. (Note: as I am typing this, Britain is experiencing its highest ever recorded temperatures: +40 degrees Celsius; this is something I find hard to imagine).

Drilling down to more specific ecosystem effects, the IPCC Working Group Report II⁵ demonstrates multiple impacts within three broad categories: ecosystem structure, species range, and phenology (timing of biological events, like breeding) and divides this further into ‘Terrestrial’, ‘Freshwater’, and ‘Ocean’, and then tracks these impacts across 14 regions and biomes, as well as globally and for biodiversity hotspots. As can be seen, the figure is mainly populated with dark blue circles, representing impact and impact due to climate change; it is largely ‘across the board’.

Every one of these climate impacts and regions deserves individual attention, but for now we will have to confine ourselves to one example, an example mentioned previously in T10: fire. We will explore this in 10.4.

¹ IPCC. 2021. Summary for Policymakers. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., et. al. (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, USA.

² Global Footprint Network. 2019. Carbon Footprint and Contributing Countries. < Climate Change & the Carbon Footprint – Global Footprint Network >

³ IPCC. 2014. Climate Change 2014: Mitigation of Climate Change. Geneva, Switzerland.

⁴ Global Footprint Network. 2021. < City and Regional Work – Global Footprint Network >

⁵ IPCC. 2022. Climate Change 2022: Impacts, Adaptation and Vulnerabilities – Summary for Policy Makers; Working Group II Contributions to the Sixth Assessment Report of the IPCC. WMO, UNEP, Geneva, Switzerland.