I’m not a scientist but am naturally curious about how the world works. I’d like to think I am open-minded and ready to question the quality and consistency of the evidence rather than take it at face value. I’ve tried to write this in a reasonably accessible way without myriad references to scientific papers.   

Science and policy changes is a progressive thing that benefits from counter-arguments. Concensus must be questioned – remember flat earth, earth at centre of universe

Moving picture. Range of positive and negative factors as technology, and the price of technology changes, new discoveries are made. 

To 2025 there has been an~1.3 degrees Celsius in the underlying global average temperature  since pre-industrial times.  years of emissions at current rates will take this to 1.5 degrees and a further 20 years to 2 degrees. Current predictions for a global average temperature increase of 2.5 degrees Celsius by the end of the century.

Reporting of these issues can leave you feeling more or less optimistic and in turn making it seem less of a clear and present danger than it is. (why is there optimism when co2 increasing). Social media search algorithms mean that people that hold views on the existence and causes of climate change have these views constantly reinforced

 How warm the globe is is affected by 

• The gases in the dry atmosphere that cause warming
• Air pollution particles known as Aerosols
• Solar radiation reaching the earth 

Human-caused emissions of aerosols, particularly Sulphur dioxide from burning coal and fuel oil have masked global warming, particularly since the 1950s,   because they reflect sunlight and  increase cloud formation, both of which have cooling effects. The same effect comes from volcanoes. The particles do not remain in the atmosphere for long as they are washed out by rain. The cooling effect, estimated at 0.5 degrees Celsius, is now reducing as sulphur emissions from coal-fired power stations and shipping fuel oil have reduced. 

The issue is the cumulative amount of CO2, (which is by far the largest component), Methane and Nitrous Oxide. These stay in the atmosphere. Natural processes over geologic time-scales change the levels. The problem is the speed at which we have been putting greenhouse gases into the atmosphere.

A direct relationship between carbon in atmosphere and warming has been established. Historic weather has been warmer – middle ages, roman warm periods.

How do greenhouse gases trap heat

1900-1940 temperature rise, 1940-70 cooling, now rising

\is it clear CO2 drives temperature

has cloud cover changed over time – more driver of warming than Co2. Warm air holds more water but does it rain more meaning sky no more cloudy

Solar patterns – 

Are surface temperature recordngs reliable – a lot of readings from stations which are increasingly in warmer urban areas – if take rural temperatures alone. Are satellite records consistent with ground

This does not mean year to year climate moves in a straight line. Natural effects such El Nino and solar radiation can have have a multi-year effect 

Warming is occurring in the Troposphere (lower atmosphere) and cooling in the Stratosphere (upper atmosphere) is consistent with trapping greenhouse gases 

An estimated 2.5 trillion tonnes of CO2 have been emitted since the beginning of the industrial revolution. Each trillion tonnes of emissions is linked to a half degree rise in global temperatures. Current emissions of 40 billion tonnes of CO2. 10 billion tonnes is absorbed by the oceans. 10 billion tonnes is absorbed by the land, photosynthesis creating organic matter which is absorbed into soil, wetlands and lake sediments.

With 8 billion people wanting electric light, to eat more meat, to have TVs, refrigeration, air-conditioning, AI and cars. 

If there wasn’t Carbon Dioxide, Methane and Nitrous Oxide  in the atmosphere the earth would be around 15 degrees Celsius colder on average than it is today. The ‘blanket’ of these greenhouse gases around the earth is now approaching twice as concentrated as pre-industrial levels (~530ppm vs ~275ppm Carbon Dioxide equivalent). We have a good record of the composition of the atmosphere far back in history from trapped air bubbles in ice cores that date back over a million years   This is conceptually what is behind the observed underlying rise of ~1.3 degrees Celsius in global average temperatures  since pre-industrial times. This warming rate has escalated significantly in recent decades. 

Feedback loops can increase the rate of warming 

• Reduced artic sea ice with the sea absorbing heat compared to the ice that reflected it. 
• Methane released as permafrost in the tundra melts.
• Droughts needing desalination plants which are energy intensive

Carbon sinks reducing

No guarantee that the ocean and land absorbtion of CO2 will continue at its current rate. 

Decay of biomass that releases carbon increases with warming. Warmer oceans less effective at absorbing CO2 and taking Co2 to the ocean floor.  

Deforestation (how can the land continue to absorb a quarter of CO2 emissions when no net increase in forest cover and desertification happening). Only partially offset by more CO2 being better for growth

Consequences

The increase of 1.5 degree that we have experienced so far might seem to many of us to be, on balance rather a nice thing. Hell, it might even help stave off the next glaciation, a natural, predictable phenomenum that occurs every 40,000 years or so and next expected in about 10,000 years. Within geological eras the climate naturally cycles between predictable interglacial periods (like now) and glacial periods. This is due to small  variations in the orbit and tilt of the earth

• More extreme weather events (how can we be sure)
• Decline in ice sheets – 2024 the Arctic sea ice is the lowest extent on teh 47 year satelite record.
• More serious forest fires
• Increase in droughts
• Ocean acidification killing Coral Reefs and reducing sea life
• Reduced biodiversity on the land and sea
• Reduced impact of the Atlantic Meridional Overturning Circulation (the ‘Gulf Stream), which will in turn cause much colder winter temperatures in Europe
• Impact on feed production (the world is largely reliant on wheat, maize, rice and soya)
• Sea level rise from melting ice – what is impac from thermal expansion of seawater from temperature rise
• Population displacement – from low lying land (pacific islands. vietnam, Indonesia) that cant survive with sea level rise to big cities cant survive without water.  

All of these effects have already been observed, but they are likely to get more extreme past 2 degrees warming. 

Tipping points – self-reinforcing

• Ice sheet collapse
• Very large-scale Permafrost thaw
• Ocean absorbtion
• Land absorbtion
• Significant decline in AMOC 

 The ups and downs of weather  – global warming exaccerbating heat in a season, droughts in multiple successive years. With 8 billion people spread across the planet, it can easily affect millions somewhere.

Solutions 

Renewable energy- price of solar has fallen dramatically

Battery storage to make best use of renewable energy- again price is falling

Geothermal

Hydropower – already well utilised

Nuclear fusion / SMRs providing baseload power that is not

Planting trees – but not a permanent solution

Bionass storage to sequester carbon – while avoiding competing with food production and changing land use in a way that reduces existing absorbtion of carbon. Biochar

Carbon Capture and storage – only known way to permanently remove carbon dioxide from atmosphere  ultimately may be needed to suck carbon out of teh atmosphere, but demands huge energy to extract when the concentration is measured in only the hundreds of parts per million 

Geo-engineering – Significant potential for conflict

What we can do personally – home insulation, solar & battery power fewer car and plane journeys, eating less meat

Science and policy to implement change are different things. Doing these things has to be politically acceptable. No one wants to be forced to do things. Damage to the economy is real. Stopping North Sea oil drilling seems illiterate. The oil will simply come from petro-states where the economic incentive it to get it out of the ground as fast as possible while maintaining good prices. 

Personal self-interest hard to overcome. Easier for middle class for whom it may be a modest inconvenience/expense, but not for people that are surviving day-to-day

International climate action

G20 accounts for 77 of emissions

UK in strong position in part because

• it cut coal-fired power generation first for a range of reasons – of which envionment was way down teh list – this partticularly took place since 1990 which conveniently is the internationally recognised benchmark year. 
• Decline in energy intensive industry which was exposed to global markets  from an earlier stage, with these goods now sourced from China etc, again particulalrly in evidence since 1990 

China

USA

Russia

Indonesia

If I were King

Exercise the precautionary principle – there as been a decline in teh worst 

Why are coal plants being built when cheaper alternatives – projections for worldwide coal generation. Twice as much CO2 from coal as from gas

If we are going to subsidise for environmental reasons Foster solar and battery where it can make most impact – Africa – global equity – the industrialised countries got rich on the back of fossil fuels – poor reaping the consequences

Strengthening and interconnecting electricity grids to maximise renewable power that can be connected and produced 

Research in CCS and geo engineering

Tax environmentally wasteful consumerism 0 swimming pools? Air con, oil, Road Tax on inefficient cars, 

Revisit government climate change plans – Policy to achieve net zero by 2050 is a signal to other countries and the carbon budgets it contains to progressively reduce net carbon emissions compared to 1990 levels are the key reference for assessing  international action via IGPCC and COP.

 assuming more sustainable aviation fuel seems over ambitious, cheaper industrial electricity prices by switching  from gas?)

cost of achieving the final stages to reach net zero by 2050 are prohibitive requiring expensive subsidy – better to spend that money in the developing world where get a much bigger ‘bang for your buck’

Price signals will mean that EVs can have an increasingly important role in demand / supply balancing drawing power when renewable output is highest

A lot of research ends up nowhere