|[ click on images to enlarge ]|
The 2015 Paris Agreement mandate: Holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels by undertaking rapid reductions in emissions in accordance with best available science.
Many assume that the temperature rise will only threaten to cross 1.5°C above pre-industrial in the second half of this century and that by that time action will have stopped the temperature from rising, with the idea that an increase in carbon sequestration could make up for remaining emissions and avoid dangerous climate change.
The question is whether such assumptions and decisions are indeed based on best available science, as opposed to political whim. Indeed, politicians are vulnerable to collusion with lobbyists feeding suggestions that there was a carbon budget to divide among polluters to enable polluters to keep polluting for decades to come. Local People's Courts can best rule on such questions, after taking a closer look at points such as the following:
- Rise from pre-industrial - While many politicians keep pushing the idea that 1.5°C above pre-industrial hasn't been crossed yet, we may already have crossed 2°C above pre-industrial, as discussed in this analysis.
- Policy choices - emission reductions are best achieved early, rather than late. Yet, many politicians keep supporting fuel (fossil fuel and biofuels) and envisage burning of fuel to continue well beyond 2050 (combined with BECCS). Instead, when taking into account damage to health and the environment, and the danger of runaway temperature rise, it should be clear that better policies must be implemented soon, such as local feebates, to support better methods and technologies such as biochar, heat pumps and eVTOL air taxis.
- Rising emissions - Politicians claim that merely stating to aim for net-zero emissions will suffice to reduce emissions, whereas the evidence shows that energy-related greenhouse gas emissions have started to grow again, following minor Covid lockdown-related reductions in 2020, as illustrated by the image below, from an earlier post.
|[ Global energy-related greenhouse gas emissions 2000-2022, adapted from EIA ]|
- Carbon sink loss - Carbon sinks have long been taking carbon out of the atmosphere, but they are struggling and many may turn from sinks into sources and instead add carbon to the atmosphere. In 2023, nearly 2bn tons of carbon is estimated to have already gone up into the atmosphere in Canada up to now due to forest fires, far exceeding annual emissions tied to Canada’s economy (i.e. 670m tons). As temperatures rise, trees become more vulnerable to diseases and insects such as bark beetles. A 2020 study shows that at higher temperatures, respiration rates continue to rise in contrast to sharply declining rates of photosynthesis. Under business-as-usual emissions, this divergence elicits a near halving of the land sink strength by as early as 2040. As temperatures rise, soils and vegetation will lose moisture to the atmosphere. The Land Evaporation Tipping Point can get crossed locally when water is no longer available locally for further evapotranspiration from the soil and vegetation, with the rise in land surface temperatures accelerating and vegetation decaying accordingly. Higher temperatures result in more extreme weather events, such as fires, droughts, storms, flooding and erosion, that can all contribute to further decrease the terrestrial carbon sink. The ocean is also struggling as a carbon sink, in part because increased river runoff and meltwater lowers alkalinity levels. Furthermore, warmer water holds less oxygen and is becoming more stratified and thus less able to supply nutrients to help plankton grow and store carbon.
- Hydroxyl loss - There is a danger that hydroxyl, the main way that methane gets broken down in the atmosphere, is declining or getting overwhelmed by the rise in methane, as described here.
- Heat sink loss - This recent study and this one warn that AMOC (the Atlantic meridional overturning circulation) is slowing down faster than expected. A recent post warns that this can contribute to more hot water accumulating in the North Atlantic, as opposed to moving to greater depth. The post also warns that, as temperatures rise, less heat gets stored in oceans, because stratification increases and more heat can get transferred from oceans to the atmosphere as sea ice disappears. There also are indications that, over time, proportionally more heat is remaining in the atmosphere, while less heat gets stored on land. All this results in a hotter atmosphere.
- Albedo loss - Loss of sea ice, loss of snow cover and warming oceans causing fewer bright clouds combine to reflect less sunlight back into space, as discussed here and here.
|[ from: When will humans go extinct? ]|
Feedbacks - Important also is the accelerating rate of change. In many respects, we're in uncharted territory and changes are occurring faster than ever in Earth's history, which should be reason for caution and even more reason to plan ahead!
[ Two out of numerous feedbacks ]
The danger is growing that feedbacks are kicking in with ever greater ferocity, i.e. non-linear change. The image on the right, from an earlier post, illustrates how two self-reinforcing feedback loops can contribute to accelerate the Arctic temperature rise.
[ click on images to enlarge ]
Tipping Points - An even more dramatic form of non-linear change occurs when tipping points get crossed, and the consequences can be catastrophic for the entire world.
[ see the Extinction page ]
The above image, from an earlier post, illustrates the danger that, as the latent heat and seafloor methane tipping points get crossed, the ocean temperature will keep rising as huge amounts of methane get released in the Arctic.
It is essential to assess the danger of events and developments such as heat reaching and destabilizing methane hydrates contained in sediments at the seafloor of the Arctic Ocean, as discussed in many earlier posts such as this one.
Seafloor methane is one of many elements that could jointly cause a temperature rise of over 10°C, in the process causing the clouds tipping point to get crossed that can push up the temperature rise by a further 8°C, as illustrated by the image on the right, from the extinction page.
Ominously, very high methane levels continue to be recorded at Barrow, Alaska, as illustrated by the NOAA image below.
Alarms bells have sounded loud and clear, such as here, warning that the temperature rise could be more than 3°C as early as in 2026. The precautionary principle should prevail and the looming dangers should prompt people into demanding comprehensive and effective action to reduce the damage and to improve the situation. To combat rising temperatures, a transformation of society should be undertaken, along the lines of this 2022 post in combination with a declaration of a climate emergency.
• NOAA - Barrow Atmospheric Baseline Observatory, United States
• Transforming Society
• Climate Plan
• Climate Emergency Declaration