With climate change, air temperatures are rising, the number of hot days and heat waves is increasing, and frost days and cold waves are decreasing. When do heat waves become a danger to humans and when is hot even too hot?

Climate change is affecting our environment in many ways – heat is one change that we have particularly felt this year. Heat waves are getting stronger, lasting longer, becoming more frequent and hotter: the past few years have been the warmest since weather records began. Climate models predict that the rise in mean annual air temperature will lead to even hotter summers in the future. In Germany, for example, there are already reliable indications that the maximum air temperature will shift toward extreme heat. In southern Germany, up to 30 hot spells per year are expected by the end of this century (Sustainability Times; Umweltbundesamt; KLUG).  

Heat stress and high ground-level ozone concentrations during heat waves also increase illness and mortality risk: according to the Lancet Countdown (2018), 30,000 additional heat-related deaths are already expected in the EU by 2030 (KLUG). 

aware_ has taken on the topic, looked at how hot is too hot and what can be done about it. 

heat waves

The human body 

To understand why heat is such a big problem, let’s take a look at what happens in the human body when it is exposed to extreme heat. Our organism strives to keep its temperature constant at around 37 degrees Celsius. This temperature may only fluctuate slightly. If the outside temperature rises, the body adjusts accordingly, the blood vessels dilate, and the skin begins to sweat. However, in the case of long and intense heat, this natural temperature regulation no longer functions properly. Blood pressure drops, blood circulation deteriorates, and the body loses fluids and salts. This puts particular strain on the circulatory system. The heart has to work harder to pump blood to the skin to dissipate the heat (t-online; ÄZQ; Sustainability Times). 

Temperature and humidity play a special role here: at very high humidity the sweat on the skin can no longer evaporate. The so-called wet-bulb temperature describes the lowest temperature that can be reached with evaporation – in an environment with a certain temperature and humidity. This value is central to our thermal regulation. Below this limit, the body is able to maintain a relatively stable core temperature over an extended period of time. If the wet-bulb temperature is too high, we can no longer release heat to the environment. And if it continues to rise, the risk of heat-related illness increases, and the body can become fatally overheated (NZZ; Sustainability Times). 

But how hot is too hot? 

Among other studies, a recent study on young healthy people by the Noll Laboratory at Penn State University shows that the upper environmental limit is even lower than the previously assumed 35 degrees. It is more like a wet-bulb temperature of 31 degrees. That would be equivalent to 31 degrees at 100 percent humidity or 38 degrees at 60 percent humidity. Current heat waves around the globe are approaching, if not exceeding, these limits (Sustainability Times). 

The German Weather Service defines a “hot day” as a day whose highest temperature is above 30 degrees, and a “tropical night” as a night whose lowest temperature does not fall below 20 degrees (Umweltbundesamt). 

In addition to the temperature, the length of a heat wave is also significant. If the value is above 32 degrees, physical activity can become dangerous. At 35 degrees or higher, there is an acute danger to life. This is because at this point the human cooling mechanism fails completely. Experts estimate that even a healthy person resting in the shade can survive a wet-bulb temperature of 35 degrees for only about six hours (NZZ). 

In May of this year, temperatures of over 34 degrees were recorded in the Indian state of Kerala. This is a record in this area. The highest values are measured in the Gulf region. There, this value approached 35 degrees in 2015. For reference, a wet-bulb temperature of 35 degrees is reached when the air temperature is 45 degrees, and the relative humidity is 50 percent (NZZ).

heat waves

What happens when it is too hot? 

These temperatures harbor a high potential for damage to humans and the environment. As previously mentioned, the body’s own cooling system can be overloaded in hot conditions. The result is regulatory disorders and circulatory problems with typical symptoms such as headaches, exhaustion and drowsiness. Elderly people and people with chronic pre-existing conditions are particularly affected by these symptoms. Across Western Europe, an estimated 70,000 more people died between June and August in 2003, one of the hottest summers in recent years, than would have occurred in a summer without a heat wave. Italy and France were particularly hard hit, with almost 20,000 heat deaths each (NZZ; Umweltbundesamt). 

In addition, high air temperatures combined with intense solar radiation promote the formation of harmful ground-level ozone. Together with particulate matter and nitrogen oxides, the mixture irritates the mucous membranes of the lungs or eyes and acts as an accelerator for lung disease (ZEIT). 

Extreme heat is also considered a general stress factor that is detrimental not only to physical but also to mental health. This phenomenon is probably based on a mixture of biological factors and psychological influences: everyday life becomes more ponderous; we get less done and are more easily distracted. If we also experience sleep disturbances at night because the environment hardly cools down, the brain lacks important rest phases that are crucial for memory formation. From a biological point of view, there are several theories, for example that heat could lead to the activation of tiny inflammation foci in the brain, which could disrupt or even damage the communication between the nerve cells. But it could also be because heat upsets the metabolism of neurotransmitters such as dopamine or serotonin, whose balance is enormously important for our feeling, thinking and even the body’s own thermostat. In addition, there is the fear of the future. And rightly so: Humanity is in danger. All the more important to take active countermeasures now (ZEIT; NetDoktor). 

What can we do? 

The most important thing, of course, is to tackle the causes by reducing emissions as quickly and effectively as possible. Climate-friendly alternatives to energy-intensive air conditioning systems are used in southern Europe, for example: There, buildings have thick walls and are often overgrown or surrounded by plants that serve as natural air conditioners and cool their immediate surroundings by several degrees (GEO).  

We ourselves can take preventive measures to protect ourselves from extreme heat. These include staying hydrated, avoiding alcohol and caffeine, eating a light diet rich in minerals, taking lukewarm showers, foot baths or damp cloths, wearing airy clothing, and staying in cool, shady places and avoiding direct sunlight (ÄZQ). 

In Germany, the federal government has developed a precautionary climate adaptation strategy with measurable objectives, following on from the 2015 Paris Agreement, which sets targets for adaptation to the consequences of climate change in addition to climate protection measures. Official heat warnings from local weather services can warn the public in advance of prolonged periods of heat (BMBF; Stadt Erkrath).

– by Marie Klimczak 

When the wind blows from east to west in the Gobi Desert singing can heard as the grains of sand vibrate together with a layer of silica to make a deep hum. The desert – a vast expanse in northern China and southern Mongolia – is known for its breath-taking dunes, mountains, and rare animals, such as snow leopards and Bactrian camels. 1,580 metres above sea level, spanning across 1,295 million square metres on land, the Gobi Desert is also home to the Gansu Wind Farm: the largest wind farm in existence. “With a planned capacity of 20GW, it’s the world’s largest wind farm in the world” (Nesfircroft). The project, worth a reported 17.5 billion USD, “will be home to 7,000 turbines and will produce enough energy to power a small country” (Nesfircroft). Thanks to the increased introduction of renewable energies, CO2 emissions have been massively reduced over recent years, but the existing carbon content in the atmosphere is too high to avoid catastrophic climate change. The latest IPCC report warns that limiting global warming to 1.5 degrees by 2100 will require “large-scale deployment of carbon dioxide removal measures” – beyond the increase of renewable energy (BBC). 

Carbon capture is the process of capturing carbon dioxide before it enters the atmosphere. This can be done through a variety of methods; Carbon Engineering’s system uses a fan to drag air (containing 0.04% CO2) across a filter soaked in a potassium hydroxide solution. The filter then absorbs CO2 from the fanned air, which then flows to a second chamber where the liquid is mixed with calcium hydroxide (builder’s lime). The calcium hydroxide, lime, then adopts the dissolved CO2, releasing flakes of limestone. Once sieved off, the flakes are heated in a third chamber until they decompose, releasing pure carbon dioxide, which is captured and stored. At each stage of this process the chemicals employed for the process are recycled back into the process, thus creating a closed reaction that repeats endlessly without the need for waste materials (BBC). 

aware_ presents 3 leading carbon capture companies on a mission to save the planet: 

carbon capture

Carbfix Turning Carbon Capture into Stone 

Carbfix is one the leading companies in carbon capture, operating as a single company since 2020 from Iceland. Revolutionary in its field, their pilot project enabled the process of turning carbon capture into stone within a matter of years, a process that was previously thought to take centuries (MindsetCo).

Once the carbon is captured at the source of the emitter, it is dissolved in water where it interacts “with reactive rock formations, such as basalts – highly reactive rocks – to form stable minerals providing a permanent and safe carbon sink” (Carbfix). The CO2 dissolved in water is then injected into the ground, where it creates reactive rock formations of basalt. In essence, the process developed by Carbix imitates and accelerates the natural process of storing carbon in rocks. Favourable rocks, water, and a source of carbon dioxide are required to successfully transform the carbon capture into stone.

carbon capture

Climeworks Carbon Capture Directly from the Air 

Climeworks captures carbon directly from passing winds. Their highly technical system successfully captures carbon in a two-step process. Firstly, using a fan the air is drawn into the collector. Captured upon a “highly selective” filter material the carbon dioxide is then captured on the surface. After this, the captured carbon dioxide is locked in a heated to a temperature between 80 and 100 degrees, which leads to a “high-purity, high-concentration carbon dioxide” (Climeworks).

This carbon capture is then recycled, used a raw material or removed from the air through safe storage. In addition to their unique modular design that can be stacked to build machines of any size, their direct capture machines are powered solely by renewable energy.  

“The grey emissions of our machines are below 10%, which means that out of 100 tons of carbon dioxide that are captured from the air, at least 90 tons are permanently removed and only up to 10 tons are re-emitted.” 


carbon capture

Net Power Carbon Capture to Create Clean Energy 

The clean energy company Net Power has developed a four-step process to use carbon capture to generate advanced clean energy. Through burning natural gas with pure oxygen, the resulting captured CO2 is recycled “through the combustor, turbine, heat exchanger, and compressor, creating lower-cost power with zero emissions” (Net Power).

The first step is the process of burning natural gas with pure oxygen (instead of air). Pure oxygen leads to less fuel consumption and the flame temperature can be increased, leading to higher levels of efficiency. The resulting carbon capture is subsequently led to a heat exchanger, water is then removed and “pumped back into high-pressure”. After this, the high-pressure CO2 is reheated and recycled. Finally, the surplus CO2 from step 2 is captured and prevented from entering the atmosphere.

“The resulting CO2 is recycled through the combustor, turbine, heat exchanger, and compressor, creating lower-cost power with zero emissions. 

Captured CO2 is pipeline ready and can either be cheaply sequestered or sold to industries such as the medical, agricultural, and industrial sectors.” 

– Net Power

– By Kim N. Fischer

News of global warming is constant, particularly in the wake of the most recent IPCC report. The intergovernmental panel on climate change (IPCC) demonstrates in its 2022 reporting that “the world faces unavoidable multiple climate hazards over the next two decades with a global warming of 1.5°C/2.7°F” (IPCC). The report goes on to warn that if global warming exceeds 2°C (3.6°F), local efforts to solve climate change will become futile. To address key issues surrounding global warming we first have to understand the main contributing factors.

aware_ presents 9 causes of global warming.


89% of fish in our oceans have “overfished” status. On average, each person eats approximately 19.2kg of fish a year, which is more than twice the amount 50 years ago. Overfishing has become a key contributor to global warming as reduced marine life in the sea leads to less carbon sequestration – “a vital process that locks carbon emissions away” (Greenpeace).  


The industrial revolution (1760 – 1840) introduced “the use of machines and the mechanisation of process” (ResearchGate), with it came “technological innovations, rapid transportation of economies, territorial expansions, unprecedented population growth, emergency of urban areas” (ResearchGate). The industrial revolution allowed for a scalability that humans had never enjoyed before, at the sacrifice of our environment. Population growth as a product of the industrial revolution has led to the expansion of urban areas, leading to increased release of greenhouse gasses, with fossil fuel burning experiencing a severe increase to satisfy energy requirements (ResearchGate).

global warming


With rising populations, the pressure on the farming industries has only increased. At every stage of the process of supplying food – producing, storing, processing, packaging, preparing and serving – “releases gases into the atmosphere” (EEA). Methane produced by livestock is one of the key contributors to global warming. Produced by livestock, methane gases escapes into the atmosphere, as well as into stored manure and organic waste. According to a report in 2012, “agriculture accounted for 10% of the EU’s total greenhouse-gas emissions in 2012” (EEA) 


It’s no secret that our careless treatment of both clothing and the apparel industry has had an irreversible effect on global warming. And there seems to be no sign of slowing down, according to recent statistics, “clothing consumption will rise by 63% by 2030, equivalent to 500 billion more shirts” (Herbones). The process of manufacturing fast fashion – trend replication using a high volume of low-quality materials – involved processes that greatly contribute to global warming. The mass-production of cheap clothing, including dying, synthetic materials, large-scale transportation and cheap, fast labour, making fast-paced clothing consumption one of the worst areas of impact.  


The key contributors to global warming are not mutually exclusive. Transport is a fundamental enabler for the apparel, farming and fishing industries alike. The shipping sector alone transports 80% of the volume of world trade (UN), contributing to an estimated 3% of global warming. In total “transportation accounts for about 29 percent of total U.S. greenhouse gas emissions” (EPA) with last 30 years demonstrating an unparalleled increase in greenhouse gas emissions. 

global warming

Oil Extraction 

On the event of any climate march or demonstration, a sea of protest signs will be emblazoned with calls to halt oil extraction. There is good reason for this. The extraction of from beneath the earths surface has a direct impact on global warming. Once the oil or gas has been taken, water fills the void where the oil or gas once existed. The water replacement is a less effective insulator, and thus more heat is conducted from the earth’s interior, “causing the land and the ocean to warm”. (The Conversation) 

Power Plants 

Power plants are responsible for approximately 40% of global CO2 emissions. To generate electricity, fossil fuels must be combusted to generate the heat needed to power steam turbines. The burning of this fuels results in the production of carbon dioxide. Increased levels of carbon dioxide are primary reason for global warming as heat is trapped within the earth’s atmosphere (Hindawi).

global warming


In the US alone 250 million tons of waste is produced every year, approximately 4.4 pounds of waste generated per person every day (National Geographic). Some scientists would argue that the levels of waste generated by growing populations is the main cause of global warming. The heat generated by waste – a result of biochemical processes and decomposition of organic constituents in wastes as well as due to chemical reactions that occur within the wastes – is a key contributor to the earth’s rising temperatures (Science Direct).  


Forests, woodland and jungles are a pillar for keeping the planet healthy. Trees take in and store carbon from the earth’s atmosphere, making them essential antidote to the dramatic increases we’ve seen in increasing levels of CO2 emissions. But these essential instruments needed to absorb carbon are being destroyed to make space for agricultural expansion, wood extraction and infrastructure expansion. One degraded or cleared by fire the stored carbon is released back into the earths atmosphere as carbon dioxide, thus contributing to global warming (LSE).


– By Eliza Edwards