Urban

Nature-based solutions: How cities can use nature to manage climate risks. c40  Research ReportsDecember 2023 From extreme heat to floods, the impacts of climate hazards on urban lives and livelihoods are already worsening. Nature-based or ecosystem-based solutions1 can help to tackle many of these risks, while offering additional benefits for health, wellbeing and urban economies. Efforts to create or revive urban nature are already reducing negative climate impacts and boosting people’s quality of life around the world. This article explains how your city can design and implement nature-based solutions (NbS) to climate risk.

Identify green assets, gaps and opportunities as part of a climate risk assessment

Map and assess the city’s climate risk and vulnerability. A climate risk assessment is a core part of climate action planning, providing the evidence base needed to effectively adapt to climate change and manage evolving climate-related risks. It will identify populations, infrastructure and assets at risk due to climate hazards – now and in the future.

Map and assess your city’s natural profile and characteristics, as well as relevant urban trends, if this has not been included as part of the climate risk assessment. This analysis is critical for designing locally appropriate nature-based solutions to climate risk. These assessments will identify needs and opportunities to upgrade and expand green space and infrastructure across the city. Good examples include the mapping and analysis conducted by Rotterdam, Melbourne, Paris, Buenos Aires and Austin.

To understand your city’s natural profile and characteristics, draw on land use maps, local knowledge and datasets to:

• Map and characterise existing green space and canopy cover to produce a baseline natural vegetation inventory. This will provide a clear understanding of the quality, character and distribution of green space, including gaps in access across the city.
• Map man-made permeable and non-permeable surfaces.
• Map native natural ecosystems, particularly the native vegetation and natural water courses and water bodies that existed before the city’s foundation. Water often flows along natural pathways even if they have been built over, so this knowledge is valuable for designing nature-based flood solutions, while the planting of non-native species risks making the ecosystem more fragile.

Seek access to data held by national government departments, local universities and non-governmental organisations to support this work. If possible, consider purchasing risk data from insurance companies. Tools such as the CORINE Land Cover data and theUrban Atlascan support cities that don’t have their own land use databases.  How to expand your city’s tree canopy cover provides more detailed advice on mapping and assessing the health of tree canopy.                                                                              Analysis of trends in your city should include....there's much more   https://www.c40knowledgehub.org/s/article/Nature-based-solutions-How-cities-can-use-nature-to-manage-climate-risks?language=en_US

Cities are tackling rising heat – but they have to avoid a dangerous trap.Guardian Chris Michael Thu 15 Aug 2024 Beneath the streets of Seville – the city nicknamed “El Sartén”, the frying pan of Europe, where summer temperatures regularly top 40C – a €5m (about £4m ) cooling strategy is taking the city back in time. The millennium-old Persian technique of “qanat” features underground channels filled with water and shafts that bring the cooler underground air to the surface. Seville is doing the same, adapting a 1992 experimental qanat to use renewable power and – in a new twist – pumping the water to the tops of buildings, where it will trickle down inside the walls to cool them. Even the benches will be chilled. It sounds like a luxury, but it is nothing of the sort. Heat has become a leading health threat to cities, and not just in Seville. Last year645 people died from overheating in Phoenix. Counterintuitively, the fire trucks in Phoenix now carry ice, packed into body bags. Its first responders have learned through the experiences of the past few years that you can save lives by packing overheated people into ice – a cold-water immersion therapy used in extreme endurance tests, such as military training and marathon running – in order to bring their temperature down rapidly while whisking them to hospital. Nor is Phoenix an outlier. On this year’s hajj, the Muslim pilgrimage to Mecca, an estimated 1,300 people died in heat that surpassed 51C – more than half way to water’s boiling point, a toxic level that cooks human cells, thickens blood and cuts off oxygen to the brain. Extreme heat in New Delhi has killed more than 100 people in the last three months alone, probably a vast undercount. It is now considered unsafe to work outside at all in Doha, a factor behind the deaths of an estimated 6,500 migrant workers in the 10 years after Qatar won the right to host the World Cup.   

Some cities now offer cooling centres, where you can escape the heat, though most people do not want to use them on a regular basis. There are policy changes that can help: laws protecting workers, heatwave response plans, and spatial mapping that can identify the hottest parts of a city. Cities are not just where the rapid heating of our planet is highest, owing to the concentrating effect of concrete and asphalt and the relative lack of natural cooling factors such as lakes, soil or shade. They are also where our increasingly urban species will have to face it. So the architects, planners and politicians who serve those cities are seeking ways to either reduce or mitigate that heat, such as the qanat cool water beneath the streets of Seville.An increasing number of cities are experimenting with green roofs, covered in plant life, or “white roofs” like those in New Delhi, where exposed concrete is whitewashed. And the architects are letting their imaginations run Much is made of tree-planting, such as Singapore’s effort to seed more than 7m new trees, and of green space in general: parks and gardens can, and do, offer a huge amount of relief. Seville and other cities are installing awnings along streets for shade; LA is one of a number of places experimenting with “cool pavements”, employing a type of paint that can reduce heat up to 11C.

An increasing number of cities are experimenting with green roofs, covered in plant life, or “white roofs” like those in New Delhi, where exposed concrete is whitewashed. And the architects are letting their imaginations run wild; in Abu Dhabi, for example, Arup has designed a tower that has computer-controlled folding screens that open and close like flowers, based on the sun’s position.wild; in Abu Dhabi, for example, Arup has designed a tower that has computer-controlled folding screens that open and close like flowers, based on the sun’s position......read on  https://www.theguardian.com/environment/article/2024/aug/15/cities-are-tackling-growing-heat-but-they-have-to-avoid-a-dangerous-trap

Measure urban heat and vulnerability to understand the heat risk Cities need information on which areas of the city, and which groups of the population, are most at risk. An individual’s heat vulnerability depends on their exposure and sensitivity to extreme heat, and their ability to adapt.

How heat kills....... Sustained exposure to extreme heat can overwhelm the body’s ability to regulate its core temperature. This can lead to heat exhaustion, severe dehydration and heat stroke, a form of hyperthermia. Extreme daily maximum temperatures, high overnight temperatures, high humidity and air pollution, and the prolonged duration of a heatwave all lead to higher heat risk. There is a widespread lack of awareness of the symptoms of heat stress, which can include headaches, vomiting, dizziness and low blood pressure, and which are often mistaken for (and misreported as) other health issues. Extreme heat also negatively impacts health conditions such as cardiovascular and respiratory conditions, and diabetes. If the body’s core temperature rises too high, the heart is no longer able to maintain adequate circulation, leading to unconsciousness and, ultimately, organ failureWork with expert partners to conduct a heat vulnerability assessment – particularly, city- and/ or national-level government health and meteorological departments, and universities. Health and mortality data from local NGOs can be a useful supplement if official data is lacking. This assessment may form part of a wider climate risk assessment.

Identify the most vulnerable population groups, and the local temperature threshold at which heat becomes a threat. Identify the most vulnerable population groups, and the local temperature threshold at which heat becomes a threat.The populations that are typically most vulnerable are:

• The elderly, young children, and people with underlying medical conditions, as they are more sensitive to extreme heat. This includes pregnant women and women with babies, as breastfeeding is extremely dehydrating. Buenos Aires’ heat risk plan focuses on the elderly.
• Low-income people and those living in poor quality housing, who may have less access to water, green spaces, information, and air-conditioning.
• People who live alone. New York’s Cool Neighbourhoods strategy includes the Be A Buddy NYC programme, which encourages New Yorkers to check in on at-risk neighbours.
• Outdoor workers, who have high exposure to heat and may have jobs requiring physical exertion. Ahmedabad identified outdoor workers as well as slum communities as high-risk groups.
• Marginalised groups including homeless people, migrants, refugees, women and girls, as they may have less access to and awareness of cooling options. The city of Melbourne’s heatwave response strategy includes a focus on the homeless, based on their analysis of heat risk for homeless people.

Use temperature and health data (such as mortality rates and hospital admissions) alongside qualitative research methods to determine which groups in the city are most vulnerable, why, and the temperature thresholds at which heat becomes a threat.....and much much more......read the full report       https://www.c40knowledgehub.org/s/article/How-to-adapt-your-city-to-extreme-heat?language=en_US 

The secret ingredient in Biden’s climate law? City trees. Planting trees in cities sounds simple. Here's why the Forest Service is spending $1.5 billion on it.Grist Matt Simon  Sep 23, 2024  The Inflation Reduction Act, gives people big rebates and tax credits to switch to a heat pump or electric vehicle. But the law also contains a much-less-talked-about provision that could save lives: $1.5 billion for planting and maintaining trees that would turn down the temperature in many American cities.That money goes to the U.S. Forest Service, which has been doling out the money to hundreds of applicants, including nonprofits and cities themselves. The $1.5 billion is nearly 40 times bigger than what the Forest Service typically budgets for planting and taking care of trees in cities each year, and it’s earmarked for underserved neighborhoods. So far, the agency has awarded $1.25 billion of the funding, and is working to distribute the remaining over the next year. Going from a $36 [million] to $40 million program with urban forestry, to a little over $1.5 billion, was a substantial infusion in dollars to address things like tree equity, tree canopy, and more importantly, providing this type of funding to underserved communities,” said Homer Wilkes, undersecretary for natural resources and environment at the U.S. Department of Agriculture.