Exploring the Reasons Behind the Observed Slower Global Warming
Why do we observe a slower rate of global warming than what the climate models predict? This question often finds climate deniers in search of reasons to dismiss the consensus on climate change. However, the complexity of the Earth's climate system and ongoing research provide a clearer understanding of the underlying factors that could explain this discrepancy.
Understanding the Climate Models
Climate models are essential tools that help us understand and predict the Earth's future climate. These models are highly sophisticated and incorporate a wide range of atmospheric, oceanic, and terrestrial processes. They are designed to replicate the past climate and predict future changes, including the impacts of increasing greenhouse gas concentrations.
The Role of James Hansen's Model
One of the most significant advancements in climate modeling came with the work of James Hansen and his colleagues in 2003. They developed a new module that greatly enhanced the accuracy of existing climate models. This module, which incorporated extensive ocean temperature and chemistry data, allowed the models to more accurately replicate the past century, providing a valuable benchmark for comparison.
Delays in Warming and Emissions
The warming effect of increased greenhouse gas emissions is not instantaneous. It takes several decades for the full impact to manifest. Even if we were to magically stop all emissions today, warming would continue for about 30 years due to the residual emissions and the thermal inertia of the Earth's oceans and land masses. Since we have not yet stabilized our emissions since the start of the Industrial Revolution, we do not have adequate evidence to observe full-scale warming in the current climate models.
Delicate Balance and Feedback Mechanisms
The Earth's climate is a delicate balance influenced by a variety of factors, including changes in solar radiation and changes in the Earth's orbit. The Milankovich cycles, which are responsible for ice ages, are just one example of these delicate balances.
Carbon dioxide (CO2) is a significant greenhouse gas, but it is not the only one. Human activities have introduced CO2 into the atmosphere, but they also contribute other greenhouse gases such as methane and water vapor. The warming from CO2 is only part of the overall warming, with the rest coming from these other factors and feedback mechanisms.
Water Vapor and Feedbacks
A common misconception is that climate models ignore the role of water vapor. In reality, modelers treat water vapor as a key feedback in the climate system. Water vapor is the most powerful greenhouse gas, but its concentration increases with temperature. This creates a positive feedback loop, amplifying the warming caused by other greenhouse gases.
However, the models do not consider water vapor as a separate function but rather as a feedback mechanism that amplifies the effects of human-caused greenhouse gas emissions. The models are designed to account for this feedback, making the overall warming more significant than just the direct effects of CO2.
The Role of Human Behavior in Addressing Climate Change
Despite the scientific evidence, human behavior plays a crucial role in addressing climate change. The history of pollution shows that we often fail to act on scientific advice until the alternatives become economically viable. In the case of climate change, the renewable energy sector has seen rapid progress, making wind and solar power cheaper than fossil fuels and nuclear energy.
The shift to renewable energy is not driven by moral or ethical considerations but by the economic benefits. In 2017, utility-scale wind and solar became cheaper than all fossil and nuclear generation, both new and existing. This economic reality has driven the adoption of renewable energy, even without widespread policy changes.
It is clear that human behavior is influenced more by economic incentives than scientific imperatives. While we can work with the current situation, it is important to recognize the underlying economic factors driving change. Only by addressing these factors can we hope to effectively mitigate the effects of climate change.