Climate is defined as the average state of all weather conditions experienced or observed in any part of the earth for many years, or, in a more systematic approach, the synthesis of weather conditions in a particular area, defined by long-term statistics such as the variability and average values of atmospheric elements.

Weather and climate are different but related phenomena. Weather describes the daily conditions in a particular location, for example, one day it may be cloudy and humid and the next day it may be sunny. 'Climate' describes the average weather conditions in a place over relatively long periods (for example, 30 years). Deserts, for example, have a hot and dry climate, while the Arctic and Antarctic regions are cold and dry.

The rapid increase in the accumulation of greenhouse gases (H2O (water vapor), CO2, CH4, O3, N2O, CFC-11, HFC, PFC, SF6) released into the atmosphere by human activities such as the use of fossil fuels, land use changes, deforestation, and industrial processes in global climate change. It refers to the increase in the average surface temperatures of the earth and the changes in the climate as a result of strengthening the natural greenhouse effect.

The sun delivers about 120,000 terawatts of energy to the earth every day, about 10000 times more than humanity currently uses in all daily and industrial processes. When the sun's rays hit the earth's surface, the earth absorbs some of this solar radiation as heat in the soil and oceans. Some of this heat escapes back into space, but some are trapped by greenhouse gases such as carbon dioxide and methane, allowing the earth to be wrapped in a blanket of warm air. This is called the "greenhouse effect" and without it, humanity and living things cannot survive.

According to the United Nations Framework Convention on Climate Change, “Climate change” is defined as the change in climate as a result of human activities that directly or indirectly degrade the composition of the global atmosphere, in addition to natural climate change observed in comparable periods.

Global warming and climate change are different but related phenomena. Global warming describes the current increase in the earth's temperature. This is just one feature of climate change. Global warming is a cause of climate change. Climate change refers to many different effects of global warming on the earth's climate system. These; These include rising sea levels, melting glaciers, changing precipitation patterns, changing frequency of extreme weather events (such as flash floods and heat waves), varying lengths of seasons, and varying crop yields.

The weather conditions when the temperatures felt on hot and humid sweltering days are 40.6°C and higher are called “heat waves”. A “heat wave” warning is issued when it is determined that the heat wave will last for at least two days. When air temperatures are 6°C or higher than normal, this is called “extremely high air temperature” or “severe heat wave”.

An urban heat island is formed when the temperature in the city center is higher than the temperature of the surrounding land. Due to the absorption of long-wave radiation by the surfaces and not being propagated back, the radiation balance is disturbed in urban residential areas. Human-induced changes in cities are the source of the urban heat island. The increase in human-induced heat release, decrease in surface evaporation, changing thermal properties of city surfaces, increase in traffic and air pollution, and decrease in humidity and air currents due to the shielding effect of buildings are the most important factors behind these changes. As a result of the increase in air pollution, 'urban fog' is also increasing along with the urban heat island. The role of energy is important in the formation of the urban heat island. The radiation coming from the sun plays an important role in the formation of the heat island, the reflection of this incoming energy from the surface/ground is different in cities and rural areas. In rural areas, the reflected energy is reflected without being exposed to any physical barriers, whereas in cities this energy is significantly trapped between tall buildings and there are significant time delays in its backpropagation.

The scientific community has proven that the negative effects of climate change can be avoided if we keep global warming at 1,5°C (starting with the Industrial Revolution) by reducing emissions from the burning of fossil fuels. It has been proven that if the surface temperature of the sphere, which is 1°C today, is 2°C, the climate system of the planet will irreversibly deteriorate and sudden and extreme climate events will become commonplace and common, with negative effects on ecosystems. 2°C is the last dangerous limit for humanity and all living things, the precautionary limit has been accepted as 1.5°C to stop global warming before reaching this limit, and the international community continues to work in this direction.

The states of the world have been continuing a global struggle for nearly thirty years to find a solution to the global climate crisis. These studies are carried out under the framework of the United Nations Framework Convention on Combating Climate Change (UNFCCC), which entered into force in 1994, the Kyoto Protocol, which entered into force in 2004, and the Paris Agreement, which entered into force in 2016. The Paris Climate Agreement is the most recent international agreement adopted by the international community to combat climate change. The agreement aims to restrain the increase in the global temperature average below 2°C and if possible at 1.5°C, and each party determines the method to be followed in reaching this target with its national contributions (NDC). Countries that are party to the Paris Agreement, which entered into force in November 2016, have accepted the target of limiting the increase in temperatures below 2°C, preferably 1.5°C, to avoid the devastating effects of climate change. For this, it is necessary not to exceed a certain carbon budget. According to the analysis, with the current carbon dioxide emissions, the carbon budget for the 2°C targets will be exceeded in 20 years, and the carbon budget under the 1.5°C target will be exceeded in just 5 years. Scientists state that the downward trend in emissions should start before 2020 for both targets. The Paris Agreement gave the message to all parties involved in the fight against climate change that they should increase their collective responsibilities. The agreement emphasizes that climate action can only take place together with all stakeholders (state or non-state).

The release of gas or gas and particle mixtures into the atmosphere is called emission. Mitigation is the measures to control, reduce and contain anthropogenic greenhouse gases that cause climate change. Emission reduction means the reduction, limitation, or containment of greenhouse gas emissions in units of carbon dioxide equivalent ton (a metric ton of the global warming potential of greenhouse gases expressed in terms of carbon dioxide gas) resulting from all kinds of sector activities. In the context of climate change, mitigation refers to human-induced interventions aimed at reducing greenhouse gas sources or increasing carbon sinks. Activities to increase carbon sinks cover a broad framework including adaptation to the effects of climate change. This situation requires a multidimensional approach in the fight against climate change, both in reducing greenhouse gas emissions and in adapting to climate impacts.

Carbon is everywhere and in all living things, including humans, and is in constant motion. Carbon does not stay in one place, it is constantly moving and changing form from one part of the planet to another. For example, carbon exists mainly in the air as gaseous (carbon dioxide or CO2), it is absorbed by plants, including trees, and by the oceans. Living things on land take carbon into their bodies when they eat plants and breathe during respiration. When plants and animals die, their remains rot and dissolve; It creates carbon that is reabsorbed by the earth. The carbon cycle has kept the gas ratio in the atmosphere more or less stable for thousands of years. However, this important balance is disturbed by human activities, either by the rapid release of CO2 as it may disappear naturally or by reducing natural carbon resources, such as by cutting down tropical rainforests. This increases the amount of CO2 in the atmosphere, and since CO2 is a greenhouse gas, this process causes the temperature of the earth to increase.

The concept of “sink” was first defined as “any process, activity or mechanism that removes from the atmosphere a greenhouse gas, an aerosol or a precursor that has a role in the formation of a greenhouse gas” according to article 1.8 of the United Nations Framework Convention on Climate Change (UNFCCC, 1992). The concept of Sink Areas was first divided into six groups in the LULUCF Manual. These; are forest areas, meadow and pasture areas, agricultural areas, wetlands, residential areas, and other areas (IPCC, 2003). Forests and seas are the most important sinks that hold carbon dioxide, one of the greenhouse gases on our planet, and prevent it from entering the atmosphere. Destruction of forests and marine environments, especially underwater vegetation, negatively affects the carbon absorption capacity of these systems and increases the amount of carbon mixed into the atmosphere. The protection of these ecosystems is of vital importance in terms of the fight against climate change, as well as the sustainability of natural life.

Carbon capture and storage is a technology that captures the carbon dioxide released by power plants and industrial factories, compresses it, and transports it deep underground to a suitable storage site. This technology has a high potential to contribute to the fight against climate change in Europe and all over the world. Subterranean fields can store almost all carbon dioxide for hundreds or even thousands of years, but the technology is expensive. Some precautions are necessary to make the storage of carbon underground to be sensitive to nature (soil ecosystem, groundwater, etc.).

Carbon pollution is excess carbon dioxide from burning fossil fuels. Carbon dioxide is a natural greenhouse gas that traps heat from the sun in the atmosphere (this is called the greenhouse effect). However, although carbon dioxide is an essential part of life (for example, plants need it for photosynthesis), there is an excess of a good substance, which becomes a threat. Because the more carbon dioxide molecules in the air, the more solar heat remains enclosed. In a fossil fuel economy that burns large amounts of coal, oil, and natural gas, far more carbon dioxide is released into the atmosphere than the world's natural cycles would safely operate. Excess carbon dioxide becomes carbon pollution, which traps much more heat.

It is an emission offsetting process carried out by purchasing credits (certificates) obtained as a result of greenhouse gas emissions that are reduced or avoided through another source in any part of the world in response to greenhouse gas emissions from one source.

The carbon budget expresses the amount of carbon dioxide that can be released into the atmosphere by humans to keep the increase in average temperatures below 2°C, that is, the maximum total (historically cumulative) global greenhouse gas emissions. In short, it is the budget for how much carbon can be emitted by human-induced activities on earth. According to scientific calculations, when global warming is assumed to be below 2°C, the total carbon dioxide that can be released into the atmosphere is 3.650 billion tons. It has been calculated that since the industrialization revolution, humanity has released 2,000 billion tons of CO2 into the atmosphere. Accordingly, a maximum of 1,650 billion tons of CO2 remained. This value is called the “global carbon budget”.

It is possible to achieve economic, social, and ecological sustainability at the same time by transforming the economic structure in a climate-friendly way. The first rule of this transformation is the abandonment of the fossil fuel-based economic system. A significant part of the financial resources required for this can be obtained from the incentives spent to keep the fossil structure alive.

It is a model that aims to change the relationship between economic development and carbon emissions and to take concrete steps in the fight against climate change. Sectors that play a key role in low-carbon development strategies are listed as energy (providing energy efficiency with low-carbon technologies), transportation, the built environment (increasing the energy efficiency of buildings), waste management, and obtaining energy from waste, infrastructure, agriculture, and forestry.

A carbon tax is a highly effective pricing measure that accepts the application of differentiated marginal tax rates to various types of fossil fuels that emit different amounts of carbon per unit of energy production such as coal, oil, and natural gas. It is one of the economic instruments of climate policy. It is a dynamic and flexible tax system applied in some countries on CO2 pollutants. The carbon tax is based on the creation of a budget revenue by directly taxing some products and services (fossil fuels, etc.) of externalized social and environmental costs, and the use of this income in transition policies to a low carbon economy.

The market where greenhouse gas emission reduction certificates are bought and sold. Voluntary carbon markets; These are markets that have been developed independently of governments' goals and policies to combat climate change and have the quality to participate in carbon offsetting for all relevant segments, from the business world to local governments, non-governmental organizations, and individuals. Organizations; By calculating the amount of greenhouse gas emissions they create within the framework of their activities (by measuring their carbon footprint), they purchase the carbon certificates produced by the projects that provide greenhouse gas emission reduction to reduce and balance these emissions. In countries that cannot benefit from the flexibility mechanisms of the Kyoto Protocol, which are subject to emission trading (such as Turkey), projects for the Voluntary Carbon Market, which operates independently of these mechanisms and was established within the framework of the environmental and social responsibility principle, are implemented.

Carbon finance is defined as a resource provided to a project to purchase greenhouse gas emission reductions. Carbon markets provide the basis for the use of carbon finance; It has continued to grow since the Kyoto Protocol entered into force in 2004.

To facilitate the achievement of digitized greenhouse gas reduction targets for developed countries and to implement carbon emission reduction practices at a lower cost; Emission trading mechanisms are defined in the Kyoto Protocol to facilitate the access of developing countries to carbon finance and clean technologies. The carbon trading system is a simple mechanism. According to the system, a company or country that reduces its greenhouse gas emissions more than the determined target can sell this additional discount to another company or country. Thus, it enables developed countries to purchase emission rights from other countries or companies to achieve their greenhouse gas emission targets. With this system, greenhouse gas pollution in any region is balanced with greenhouse gas reduction in another region. For example; If a firm is causing 100 tons of carbon emissions due to electricity use and business travel, it can offset this impact by purchasing 100 tons of carbon credits to neutralize the carbon negative impact (carbon neutral).

This system is the first emissions trading program implemented internationally. The system was launched in January 2005. The European Union (EU), Emissions Trading System (European Union, Emmisison Trade System/EU-ETS) has the largest share in the world carbon market. The System, which was created as one of the flexibility mechanisms of the Kyoto Protocol, forms the basis of the EU's strategy to combat climate change. Emissions trading helps ensure that CO2 emission reduction targets are met at the least possible cost. ETS is a company that operates in EU member states and produces CO2 intensively in sectors such as power generation, oil refineries, iron and steel, cement, glass, lime, brick, ceramics, and paper (which produces almost half of the CO2 created in the EU and its thermal input is 20 MV). /s) covers more than ten thousand businesses.

Adaptation is all activities carried out to identify the current and possible future effects of climate change. Adaptation means anticipating the adverse effects of climate change and taking appropriate measures to prevent or minimize the damage they may cause, or take advantage of potential opportunities that may arise. Adaptation seeks to reduce the vulnerability of human livelihoods, economies, and natural systems to the impact of climate-induced changes. Some examples of compliance measures are; increasing the resilience of the agricultural sector against famines, reducing the risk of flooding in cities through improved infrastructure management and storage, maintaining clean water ecosystem functions, etc. applications are available. In summary, adaptation means strengthening, developing, and implementing strategies to combat the effects of climate events (risks), provide benefits, and manage the effects.

One of the important concepts in adapting to the impacts of climate change and in developing the capacity to manage risks is resilience. Resilience is the ability of a social or ecological system to tolerate disturbing situations while retaining the same basic structure and functions, its capacity to organize, and its capacity to adapt to tension and change. In this sense, resilience refers to the cycle of renewal and creative thinking that people enter while coping with shocks, stresses, and changes in different meanings, from financial crises to climate change, in the socio-ecological systems in which they are and are a part.

Although there is no direct definition of a low-carbon city; A low-carbon city model, which uses creative technologies to reduce carbon emissions and adapts to the effects of climate change, has technologies to manage the force of nature, and whose ecological integrity has not been compromised.

Urbanization poses a major threat to water resources and its cycle, as it often brings impermeable surfaces, fossil fuel use, deforestation, and degradation of ecosystems. Rain harvesting is the method of capturing rainwater and accumulating it on the ground and/or underground, in the soil, and/or in warehouses. Rain harvesting methods associated with the beginning of agriculture is a method recommended within the scope of adaptation to climate change in the 4th Assessment Report of 2007 created by the Intergovernmental Panel on Climate Change (IPCC).

Today, it is understood that urbanization and economic growth processes do not bring social and economic development to all parts of the society and that urbanization itself will ameliorate or worsen the social gap and economic or political exclusion in cities; The importance of social, economic and political inclusion and egalitarian approaches and policies for sustainable cities has become clear. Against this trend, resilience has been brought to the agenda as an important concept in terms of sustainable cities and development. Habitat III/New Urban Agenda defines resilience as a goal as well as a tool for sustainable cities and human settlements. In this context, it is important how cities should be planned to fulfill their driving role in sustainable development. Here, this need for improvement in national/local planning policies is not only affecting the cities of countries with inadequate planning systems and implementation tools; Considering climate change, globalization, demographic change, and other new pressures on planning, it also concerns countries with strong policies.

Green infrastructure is a network of green areas formed by interconnected natural, semi-natural and cultural areas that preserve ecosystem values and functions. What does city green infrastructure mean? One of the most important and successful ways of controlling flood waters is the creation of "city green infrastructure" systems. With nature-based solutions such as urban green infrastructure, the existing natural vegetation is multiplied to create qualified green areas and thus rainwater is collected.

Rainwater is both cleaned by filtering from the soil and feeds the underground water resources. The ecosystem services are provided by a green infrastructure system that includes green areas with high ecological qualities, designed to form functional links with each other, and reduce the effects of climate change. These areas, with their vegetation, provide air cooling, reducing the heat island effect, carbon sequestration and storage, cleaning the air by removing pollutants, enriching the soil with organic materials, providing food and shelter for wildlife, supporting biodiversity, and preventing the surface flow of precipitation waters. It has many functions such as feeding groundwater resources, reducing wind and precipitation erosion, filtering noise, reducing energy consumption, and increasing the recreational and real estate value of lands. In rainwater management applications, solutions are produced to control surface runoff water and to produce applications that resemble the natural water cycle. Rainwater management techniques include structures such as rain gardens, permeable flooring, dry well, rainwater vegetation strip, rain ditch, seepage pits, green roofs (roof gardens), rain barrels, and cisterns. Rainwater management has become the priority of many cities in the world to adapt to the effects of climate change in terms of water management, the term 'sponge city' has emerged as a result of studies conducted in recent years on this subject. Cities develop and implement policies to become a sponge settlement.