A Double-Edged Sword

Ambitious targets set adopted by the Paris COP21 to restrict global temperature rise this century below 2 ⁰C or preferably 1.5 ºC have failed. This has presented governments, corporations and comunities around the globe with an incentive to reducing their CO2 emissions; yet curbing CO2 emissions and temperature rise simultaneously offers an even greater challenge, or so does it seem…

The Anthropocene: A Harsh Reality

Modernity as we know it started 250 years ago with the invention of the steam engine, followed quickly by the invention of the internal combustion engine to fulfill in all of our energy and transportation needs. Therefore our reality of our modern world is deeply intertwined with fossil fuels, which have driven progress and economic development over the past two and a half centuries since the advent of the steam engine. Fossil fuels power our factories, vehicles, homes, and countless products, symbolizing economic advancement and prosperity. However, this dependency has also led to escalating greenhouse gas emissions, exacerbating climate change at an alarming rate.

Challenges of Transition: Transitioning away from fossil fuels poses a monumental challenge. It is a complex endeavor that will likely span 50 to 75 years to accomplish effectively. This transition must be managed carefully to avoid severe disruptions to societies and political stability. Rapid changes could unsettle economies heavily reliant on fossil fuel industries, impacting jobs, livelihoods, and regional economies.

Political Realities: Political leaders face significant obstacles in steering their countries towards climate-friendly policies. Measures that align with the ambitious targets of the Paris Agreement often clash with short-term economic interests and public sentiment. Promoting efficiency and reducing consumption are tough sells, particularly in societies accustomed to growth-driven economies.

Disparities in Development: Addressing climate change also highlights global inequalities. Developing nations, seeking economic growth and prosperity akin to developed counterparts, face dilemmas about the path forward. Can economic progress be sustained while reducing dependence on fossil fuels and adhering to climate commitments?

Ambition vs. Reality: Current trends in greenhouse gas emissions diverge starkly from what is required to limit global warming to 1.5 degrees Celsius, as outlined in the Paris Agreement. Despite pledges and commitments, there remains a significant “ambition gap” between stated goals and actual emissions reductions. Bridging this gap demands not only enhanced policies and technologies but also profound shifts in societal attitudes and behaviors.

Measuring Progress: Monitoring greenhouse gas emission curves provides a stark picture of our trajectory. Comparing current emissions trends (Figure 1) with necessary reductions (Figure 2) underscores the urgency and magnitude of action required. Politicians and policymakers must confront these realities and implement transformative measures to align climate efforts with the goals of the Paris Agreement.

In essence, addressing climate change requires navigating complex socioeconomic and political landscapes while embracing technological innovation and sustainable practices. It demands global cooperation and shared responsibility to ensure a sustainable future for all, despite the challenges posed by our entrenched reliance on fossil fuels.

figure 1 | Carbonbrief.org

The Keeling Curve is an iconic graph showing how levels of carbon dioxide (CO2) have been building up in the atmosphere, driving an increase in global temperatures

https://www.climate.gov/news-features/videos/keeling-curve-carbon-dioxide-levels-becomes-chemical-landmark (The history of Mauna Loa). 

In figure 1 you see the Keeling Curve, Charles Keeling (1928 – 2005) was an American scientist whose recording of carbon dioxide in the extremely pure air of the Mauna Loa Observatory confirmed mankind’s impact on the Earth, linking for the first time rising levels of CO₂ from burning fossil fuels to the warming of the planet. The Keeling Curve shows the actual development of GHG emissions from 1958 to the present day, 

Figure 2 / Alliance for Science


In figure 2 you see that we have to bend the Keeling curve (= reduce GHG emissions) in the coming years to limit warming to 1.5⁰C. Currently we keep doing the opposite: each year we are adding more GHG to the atmosphere. But the task is very ambitious: emissions  should be diminished radically while at the same time improving the economic situation of developing countries. Is this realistic given the short amount of time?

Bridging the ambition gap

Time has caught up with the facts. What we currently achieve in CO2 reduction lags considerably behind our ambitions. Figure 3 shows the ambition gap in reducing our emissions: we have to do a lot more than we currently do to come close to what we intended (reduce emissions with 19 – 23 Gigaton CO₂-equivalent extra).

Figure 3. Ambition Gap Graphic

We need emergency measures to cool our climate

Addressing the climate emergency requires immediate and concerted efforts to reduce greenhouse gas emissions while simultaneously exploring and implementing climate cooling strategies. These measures are essential to mitigate the most severe impacts of climate change, prevent irreversible tipping points, and protect vulnerable communities and ecosystems. By prioritizing both emissions reduction and climate cooling, we can work towards stabilizing the climate and securing a sustainable future for generations to come.

The current albedo collapse is almost 1% per decade. The planetary reflectance is now measured by NASA at 98 watts per square meter compared to 100 w/m2 in 2001. The dimming of the world since 2015 has the warming effect of 100 ppm of CO2 emissions, according to James Hansen, Professor Climate Science, Awareness and Solutions Program Earth Institute at Columbia University.

  • The idea of mitigation deterrence is incoherent and ideological. Reducing emissions cannot mitigate climate change in a relevant time frame, while higher albedo can. So it doesn’t make sense to say that increasing albedo could deter mitigation.
  • We have not yet seen the full warming impact of current CO2, due to the delay caused by the mixing of the oceans. This has slowed the heat for a while.
  • Reducing emissions can have virtually no effect on warming.

The Promise of Ocean-Based Climate Cooling Solutions

Fortunately, new nature-based solutions, groundbreaking research, and innovative technologies focused on ocean-based climate cooling are emerging rapidly. If further developed, they may allow us to mitigate the increase in global temperatures. Many of these initiatives consider the critical climate role of the oceans as a starting point. Among them, Marine Cloud Brightening (MCB) stands out as a promising interim technology to cool the climate, working in conjunction with other ocean-based cooling solutions.

Emerging Ocean-Based Cooling Solutions

  1. Marine Cloud Brightening (MCB):
    • Mechanism: MCB involves spraying fine seawater droplets into the atmosphere, where they evaporate and leave behind tiny salt particles. These particles enhance the reflectivity of stratocumulus clouds, reflecting more sunlight back into space and thereby cooling the Earth’s surface.
    • Potential: As demonstrated by recent trials near the Great Barrier Reef, MCB has shown promise in its ability to increase cloud reflectivity and potentially lower temperatures. This technology can serve as an interim solution while longer-term mitigation strategies are developed.
  2. Ocean Fertilization:
    • Approach: Adding nutrients like iron to certain ocean regions to stimulate the growth of phytoplankton, which absorb CO₂ during photosynthesis.
    • Impact: Enhanced phytoplankton growth can sequester significant amounts of CO₂, helping to mitigate the greenhouse effect.
  3. Artificial Upwelling:
    • Technique: Bringing nutrient-rich deep waters to the surface to promote phytoplankton blooms and increase oceanic CO₂ uptake.
    • Benefit: This can enhance the ocean’s natural carbon sequestration processes and support marine ecosystems.
  4. Blue Carbon Ecosystems:
    • Restoration: Protecting and restoring coastal ecosystems such as mangroves, seagrasses, and salt marshes, which are highly effective at sequestering CO₂.
    • Advantage: These ecosystems provide long-term carbon storage and offer additional benefits such as coastal protection and biodiversity support.

The Role of Oceans in Climate Regulation

Oceans play a pivotal role in regulating the Earth’s climate. They absorb about 25-30% of human-produced CO₂ emissions and a significant portion of the excess heat from global warming. By leveraging the natural processes of the oceans, these innovative technologies aim to enhance the Earth’s ability to mitigate climate change effectively.

Combining Technologies for Maximum Impact

The combination of MCB with other ocean-based cooling solutions could create a synergistic effect, amplifying the overall impact on global temperature regulation. By addressing both immediate cooling needs and long-term carbon sequestration, this integrated approach could provide a more comprehensive solution to the climate crisis.


The rapid development of nature-based solutions, groundbreaking research, and innovative ocean-based climate cooling technologies offers hope in the fight against global warming. Marine Cloud Brightening, in particular, shows great promise as an interim solution to cool the climate. When used alongside other ocean-based cooling strategies, it can help mitigate temperature increases and pave the way for a sustainable future. Continuing to invest in and develop these technologies is crucial for protecting our planet and ensuring the well-being of future generations.

Scenario 1, global warming without MCB Figure 1, is modelled in 2012 by British scientists. This figure shows the increase in temperatures when GHG climb from 440 ppm CO₂-equivalent to 560 ppm CO₂-equivalent.

This is where Marine Cloud Brightening can play a significant role.

Scenario 1, figure 1, Alan Gadian, Ben Parkes and John Latham., 2012 (in degrees kelvin)

Scenario 2. This scenario shows what can be expected when MCB is applied in three oceanic regions: North and South America and South Africa. Although the amount of GHG in the atmosphere remains 560 ppm CO₂-equivalent, long-term application of MCB moderates the amount of solar radiation that reaches the surface. The cooling effect is global and temporarily. Therefore it has to be repeated while other ocean-based climate cooling mitigating technologies are implemented.

Scenario 2, figure 2

Combining Climate Cooling Solutions

The combination of MCB with other ocean-based cooling solutions could create a synergistic effect, amplifying the overall impact on global temperature regulation. By addressing both immediate cooling needs and long-term carbon sequestration, this integrated approach could provide a more comprehensive solution to the climate crisis.

Is the Paris Climate Agreement still feasible?

The Paris Agreement (COP21) called for a consistent reduction of GHG emissions up to 2100 to being able to limit the temperature rise to 1.5 ºC. To reach this landmark in 2030, GHG emissions should have halved by about 25 Gigatons/annually. They didn’t.

At present it is clear this 2030 objective can no longer be achieved in the years remaining: global energy-related carbon dioxide emissions rose by 6% in 2021 to 36.3 billion tonnes, their highest ever level. In 2022 the global average carbon dioxide set a record high: 417.06 ppm CO₂-equivalent. The summer of 2023 was the hottest since global records began in 1880

Are current corporate emission reduction targets ambitious enough to meet the Paris Agreement’s 1.5 ⁰C goal? Take a look at the CDP temperature ratings 2022 analysis.

Modelling the future

  1. Current Situation: As of 2022, CO₂-equivalent concentrations are around 420 ppm. The global temperature has already increased by approximately 1.5°C on average compared to pre-industrial levels.
  2. Future Projection: If emissions continue unabated, reaching 560 ppm CO₂-equivalent by 2050 would correspond to an additional warming of about 1.4°C, on top of the warming already experienced. This means a total global warming of around 2.6°C to 2.9°C above pre-industrial levels by mid-century.
  3. Implications: Exceeding the 1.5°C threshold carries significant risks, including triggering various tipping points in the Earth’s climate system. These tipping points could lead to irreversible changes such as accelerated ice sheet melting, permafrost thawing, and disruptions to ecosystems and biodiversity.
  4. Policy Alignment: The Paris Agreement aims to limit global warming to well below 2°C and pursue efforts to limit it to 1.5°C. In addition to mitigating greenhouse gas emissions to limit global warming, policies should also focus on direct climate cooling strategies:
  5. Action Needed: To avoid the severe impacts associated with exceeding 1.5°C of warming, there is an urgent need for enhanced climate cooling action at all levels — from governments implementing more ambitious climate cooling policies, to businesses accelerating their transition to low-carbon technologies and practices, and individuals making sustainable choices in their daily lives.

Efforts to combat climate change must not only focus on reducing greenhouse gas emissions but also on actively cooling the planet through innovative technologies and strategies. Achieving the goals of the Paris Agreement and limiting global warming to 1.5°C requires urgent and comprehensive action, including scaling up both mitigation and climate cooling measures. By prioritizing these efforts, we can mitigate the risks of climate tipping points and safeguard the future of our planet and its ecosystems for generations to come.