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→B.Challenges and trade-offs
In all the scenarios outlined by the IPCC, 1.5°C of warming is likely to be reached by 2040, representing increased risk to natural and human systems compared to the present time However, even keeping to within a 2°C target is still very dependent on the level of emissions produced over the next decade and 2°C of warming is only avoided in the low emissions scenarios.
In all the scenarios outlined by the IPCC, 1.5°C of warming is likely to be reached by 2040, representing increased risk to natural and human systems compared to the present time However, even keeping to within a 2°C target is still very dependent on the level of emissions produced over the next decade and 2°C of warming is only avoided in the low emissions scenarios.
=== <big>B.Challenges and trade-offs</big> ===
=== <big>B. Challenges and trade-offs</big> ===
Without far-reaching policy, technology and behaviour changes, the world is on course for 3°C of warming or higher. A 3°C world is very different from the current one: with extremes of temperature come more pronounced risks of heat waves and drought, violent storms, rainfall and flooding, that will have serious consequences for ecosystems and societies around the world.
Without far-reaching policy, technology and behaviour changes, the world is on course for 3°C of warming or higher. A 3°C world is very different from the current one: with extremes of temperature come more pronounced risks of heat waves and drought, violent storms, rainfall and flooding, that will have serious consequences for ecosystems and societies around the world.
One concern is that large reductions in energy use could reduce living standards in industrialized, rich countries, as well as limit our ability to improve the living standards in poor countries. Improving living standards in poor countries will in some cases require increases in energy use and investment in efficient technology and public services
One concern is that large reductions in energy use could reduce living standards in industrialized, rich countries, as well as limit our ability to improve the living standards in poor countries. Improving living standards in poor countries will in some cases require increases in energy use and investment in efficient technology and public services<ref>[[Marta Baltruszewicz et al 2021]]</ref>.
Recent estimates show that decent living standards for all could be achieved while reducing global energy demand for all could be achieved while reducing global energy demand<ref>[https://www.sciencedirect.com/science/article/pii/S0959378020307512 Providing decent living with minimum energy: A global scenario Decent living gaps and energy needs around the world]</ref>as long as overconsumption is drastically brought down. Some of the ways in which this can be addressed include the need to:
# '''Increase production of clean energy from low-and no-carbon technologies, such as wind and solar, and in parallel, decrease and eliminate investment in and production of fossil fuel energy.'''
# '''Invest in efficient technologies and infrastructure (insulated buildings, public transportation).'''
# '''Ensure sufficient access to affordable energy services (i.e all the things people need to use energy for, like cooking, heating, cooling, transport and communications) for all, while reducing overconsumption of the wealthiest.'''
# '''Move to healthier diets with more regional and seasonal vegetables and fruits (to reduce emissions from agriculture).'''
# '''Remove carbon from the atmosphere through the conservation and restoration of ecosystems<ref>[https://www.ipcc.ch/sr15/chapter/chapter-2/ IPCC Special Report, Chapter 2]</ref>.'''
One study found that to have a 50% chance of hitting the Paris Agreement goal, 90% of the world’s remaining coal reserves must stay in the ground<ref>[https://www.nature.com/articles/d41586-021-02444-3 Most fossil-fuel reserves must remain untapped to hit 1.5 °C warming goal]</ref>, and no new investments in fossil fuel extraction can be made<ref>[https://www.iea.org/reports/net-zero-by-2050 Net Zero by 2050 Report IEA]</ref>.
Lack of global cooperation, as well as the persistence and growth of high-carbon lifestyles are all obstacles to achieving stability of temperature rise limited to 1.5°C. If all the current pledges under the Paris Agreement NDCs were to be met, it would still not be enough to limit warming to 1.5°C , and would instead lead to warming around 3°C – far beyond the goals of the Paris Agreement, or anything considered safe for humanity.
=== <big>C. Assumptions about negative emissions</big> ===
The low and very low emissions scenarios above rely on some level of greenhouse gas removal, through '''“negative emissions”''' technology in the second half of the century.
Many scientists are concerned that the promise of future unproven technologies, such as removal of CO2 from the atmosphere, will delay the actions that need to be taken today to address climate change. In the past, powerful industries have used the promise of future technologies to justify continued fossil fuel use<ref name=":102" />. Technologies such as ‘carbon capture’ do not yet exist at a level that is scalable, and so there are important questions about whether the technologies can be relied on.
=== <big>D. Tipping Points – Can we predict what will happen next?</big> ===
Even the best science cannot predict the future with absolute certainty. Living with climate change means living with uncertainty<ref name=":1">[https://gar.undrr.org/sites/default/files/gar19distilled.pdf 2019 Global Assessment Report on Disaster Risk Reduction]</ref>. In this section, we look at feedback loops and “tipping points” as examples of uncertainty around the future of our climate.
Imagine a glass of water being tipped over. Depending on how much water is in the glass, there will be a point where the glass is tipped so much that the water will pour out of the glass. Once the water has left the glass, it’s impossible to put it back.
Climate tipping points are a “point of no return”, when the combined effects of climate change result in irreversible damages that would “cascade” across the world, like dominos. Once a tipping point is reached, a series of events is triggered, leading towards the creation of a planet that is inhospitable for many people and other lifeforms<ref name=":82" />.
The IPCC introduced the idea of tipping points two decades ago. A possible tipping point is the melting of land ice in the polar regions (Greenland and Antarctica), leading to many meters of sea-level rise over time. Models suggest that the Greenland ice sheet could eventually disappear at 1.5 °C of warming<ref name=":82" />, although only after many years. In July 2021, a heat wave caused Greenland to lose enough ice to cover the US state of Florida in 2 inches (5cm) of water in one day<ref>[https://www.reuters.com/world/europe/greenland-experienced-massive-ice-melt-this-week-scientists-say-2021-07-30/ Reuters]</ref><ref>[https://www.ipcc.ch/srocc/ IPCC Special Report on the Ocean and Cryosphere in a Changing Climate]</ref>. Sea ice is already shrinking rapidly in the Arctic, indicating that, at 2°C of warming, the region has a 10–35 percent chance of becoming largely ice-free in the summer<ref>IPCC Special Report on Polar [https://www.ipcc.ch/srocc/chapter/chapter-3-2/ regions]</ref>.
Another possible tipping point is the large-scale destruction and degradation of rainforests like the Amazon, which is home to one in 10known land-based species. Estimates of where an Amazon tipping point could lie range from 40 percent deforestation to just 20 percent forest-cover loss. About 17 percent has been lost since 1970<ref name=":82" />, with large areas being lost due to human deforestation every minute.
Moving closer to tipping points such as ice sheets melting, deforestation, melting of permafrost and changes in ocean circulation (or a combination of these) creates a cycle which scientists refer to as a “feedback loop”, where climate change causes a cascade of effects that result in even more climate change.
An example of this can be found in the Arctic. The greenhouse gas methane is currently “stored” in Arctic permafrost. As global warming causes the permafrost to melt, the methane stored is released into the atmosphere, adding yet more greenhouse gas emissions that can lead to further global warming. More warming results in more melting permafrost, adding yet more methane to the atmosphere to create even more warming and more melting permafrost, in a vicious cycle that may be impossible to stop.
These feedback loops are “non-linear”, meaning they can accelerate in sudden and unexpected ways and could arise in a way that science has not been able to predict<ref name=":1" />. Due to these uncertainties, it is possible that we could already be at risk of triggering tipping points that lead to irreversible changes that culminate in a largely uninhabitable planet<ref>[https://www.pnas.org/content/115/33/8252 PNAS Trajectories of the Earth System in the Anthropocene]</ref>.
The next 10 years will be critical for adapting to and mitigating climate change. Being well informed about the risks and causes of climate change helps us to make the best decisions in the present, despite the fact that it will never be possible to predict the future with certainty. Climate change is happening much faster than efforts to address it, and the past is not a reliable indicator of the future<ref name=":1" />. Going forward, the future is uncertain. This understanding creates discomfort (a sense of things being out of control), but also opportunity<ref name=":1" />. There is still time to avert the crisis, if action is taken now.
== <big>Glossary</big> ==
== <big>Glossary</big> ==