“tourism’s carbon footprint could reach 5-6.5 billion tonnes of CO2 by 2025, and this figure would account for roughly 12% of current greenhouse gas emissions” - Carbon Brief explains. 
Tourism's CO2 contribution (Nature study)
The global tourism industry has undergone monumental growth over the past few decades. First-world and high-income countries along with the emerging middle class in developing countries, have seen the greatest increase in demand for luxury and air travel. The number of international tourists is growing at an annual rate of 3-5%, realistically beating the growth of international trade and construction. 
A groundbreaking study recently published in the prestigious journal Nature Climate Change, did a comprehensive analysis of the “global CO2 footprint” of tourism and quantified the carbon flow between 160 countries from year 2009 to 2013, and their results were staggering! This energy and carbon-intensive commodity accounted for far higher percentage than previously alleged. According to Dr Arunima Malik and her colleagues from the University of Sydney, tourism contributes to about 8% of the total worldwide greenhouse gas emissions! 
Many nations have adopted a misguided view and looked at tourism as a low-impact development industry, leading countries like Japan and Hungary to invest profusely into it. The US, followed by Germany, China and India are responsible for most of the inbound and outbound emissions. But for some popular holiday destinations with economies thriving on tourism, the per-capita footprints look much different. For example, islands like the Maldives, Mauritius, Cyprus and the Seychelles, have international visitors and tourists that cause 30 to 80% of national gas emissions! 
Transportation as the key factor
Of course, when the effects of tourism on climate change and global warming were investigated, all the contributing factors and components were considered—from tourism operations and services to upstream supply chains.
"We looked at really detailed information about tourism expenditure, including consumables such as food from eating out and souvenirs. We looked at the trade between different countries, and also at greenhouse gas emissions data, to come up with a comprehensive figure for the global carbon footprint for tourism." - Dr Malik says.
Yet, the major culprit appeared to be transport—and air transport to be more precise.
Air travel is a very high-emission-density activity. According to the United Nations World Tourism Organization (UNWTO), the transport sector generates about 75% of all greenhouse gas emissions and 54-75% of carbon emissions are directly attributed to air travel, and 13% to coach and rail.
“At least 15% of global tourism-related emissions are currently under no binding reduction target as emissions of international aviation and bunker shipping are excluded from the Paris Agreement,” The study states, “In addition, the US, the most significant source of tourism emissions, does not support the Agreement.” 
According to the UK’s 2018 Government GHG Factors for Company Reporting Methodology, if a single person is flying internationally in business class to his holiday destination, he can expect his carbon footprint to increase by 0.04 kg CO2e for every kilometre in the air. (Including airline catering, services and upstream aircraft fuel processes). So, a one-way 4h 30m flight from Tel Aviv to Moscow (~2,620 km) would put him at 104.8 kg CO2e. 
Travelling by car emits approximately 0.05 kg CO2e per kilometre, but travelling by sea is somewhat better, but not by much; travelling with a ferry, the rate would be at 0.02 kg CO2e per kilometre, or about half of that of international business class by air. 
Other contributors: hospitality, food, and activities
That may seem a little dreadful, but the damage is not over yet. The next big offender when it comes to CO2 emissions on a holiday would be the hospitality business. While accommodation accounts for a moderate proportion of global emissions, when assessing all the life cycle and supply chain emissions of tourism-related goods and services (e.g. air-conditioning, heating, maintenance, restaurants, pools and bars), the hospitality sector’s share of tourism greenhouse gas emissions put together jumps to 20%.  Or 1% of the global greenhouse gas emissions. 
There is where the choice of destination starts to matter—some countries are much better at regulating CO2 emissions caused by their industries compared to others. Let’s say if one is to spend the night in a hotel in Indonesia, their good-night-rest would put 126.7 kg of CO2 emissions in the air; however, if they are staying in a hotel in France, a room for one night would debt the planet only 6.6 kg CO2e. 
The Hotel Global Decarbonization report, published recently by the International Tourism Partnership (ITP), revealed that in order to meet their decarbonization goal and stay in line with the Paris Agreement to keep global warming temperature increase below the 2-degree threshold, this booming hotel business must reduce its carbon footprint by 66% percent by 2030 and 90% by 2050.  To achieve this objective, they must work on developing science-based targets for each individual hotel and establishment to deliver carbon reductions at scale.
On holiday, tasting foreign and new cuisines can be most exciting, whereas for other individuals, food and foreign cuisines can be the whole point of their vacation. While everyone agrees that a good meal is a necessity beyond discussion, the effects of food production on global warming must be seriously considered.
In a study on climate metrics and carbon footprint of livestock, it was found that 15% of global greenhouse gas emissions came from meat, poultry, dairy and egg farming.  The use of nitrogen fertilizers, the enteric fermentation (the digestion of ruminant animals e.g. cows) and things like processing, transporting, storing, cooking, packaging and disposing of food waste, all play roles in this massive CO2 bill that the planet is footing. 
When browsing the menu on a vacation, know that a kilo of lamb meat is worth 39.2 kg CO2e, beef is 27 kg CO2e and a kilo of cheese is 13.5kg CO2e.  Bearing all that in mind, a meat lover’s burger meal of a 150gr meat patty equals to 3.3 kg CO2e and a vegetarian meal is 1.7 kg CO2e. 
Depending on the recreational activities that one prefers to engage in when on a holiday, other factors can add even more emissions on the way. For example, the Ski Industry 2017 Annual Environmental Report disclosed that Ski Resorts produced 204,477 MTCO2.  Not to mention, theme parks, boat rides, bus tours, museums, shopping centres and malls all make approximately 3.5% of this fast-growing trillion-dollar industry— precise reason why all these estimates are subject to annual changes.
Combined emissions for a weekend trip in Barcelona
So, let’s try to use all these findings together, to calculate the total emissions of a hypothetical vacation: a solo traveller from London to Barcelona for 3 days by plane.
Using UK’s 2018 Government GHG Factors for Company Reporting Methodology, we find somewhat greener emissions of 0.026 CO2e, for short-haul European flights to and from the UK.  With a flight distance between the two cities of 1140 kilometres, a two-way flight between London and Barcelona in Business Class would total at 59.28 kg CO2e. Spain’s hotels average their emissions at 23.5 kg CO2e per room per night, so for 3 nights that’s 70.5 kg CO2e.  At two average meals per day, for three days, the food’s emissions would be 15 kg CO22e. And finally, with about 100 kilometres of touring, cabs, and commutes in Barcelona, the share of emissions from activities would average at about 5 kg CO2e, bringing the total emissions for our trip up to approximately 149.78 kg CO2e.
The interplay of interests in sustainability
Climate change and global warming are in a dual relationship with tourism and tourists alike, both as a victim and an offender. Requiring adaptation by all major tourism stakeholders.  Climate is the principal driver of seasonality in tourism’s demand, and has an important role in operating costs, such as heating-cooling, snow-making, irrigation, food and water supply, and insurance costs. Apart from agriculture, no industry is likely to lose to climate change, like tourism does.
Indeed, climate change is not a remote future event for tourism, as the wide-ranging impacts of a changing climate are becoming evident at destinations around the world and climate change is already influencing decision-making in the tourism sector.
“Biodiversity loss and deforestation, scarcity of water and desertification, reduced landscape aesthetic, altered agricultural production (e.g., wine tourism), increased natural hazards, melting of snow and glaciers, coastal erosion and inundation, damage to infrastructure and the increasing incidence of vector-borne diseases will all impact tourism to varying degrees,” - The UNWTO notes.
Making these destinations less hospitable and shifting their demand to other places.  Thus, climate-induced environmental changes will have profound effects on season-dependent tourism at the destination and residence base. (i.e., sun-and-sea or winter sports holidays) could have substantial implications and an increase in competitors could therefore ail the profitability of tourism enterprises. 
Mitigating climate change
The increased rates of deforestation, conventional agriculture and burning of fossil fuels has stripped the atmosphere off oxygen and clean air and has poisoned it with all types of harmful gasses and pollutants. And because of its long lifespan in the atmosphere, CO2 is the most critical gas that needs urgent offsetting.  Naturally, we can come to conclude that trees are central part of the solution to the growing amount of CO2 emissions in our globe.
Aside from substituting to greener sources of energy, tree planting and afforestation is the next best step. Clear evidence of the role of forests in regulating global atmospheric CO2 and in the offset of the increase in anthropogenic emissions of greenhouse gases and rate of global warming. 
Trees or plants in general acquire CO2 through photosynthesis and accumulate it in their biomass, in the form of organic carbon. Growing trees between 5 to 20 years, capture the most carbon. As little as one acre of reforested land sequesters and absorbs about 300 to 2,100 kg of CO2 per year, (calculating the average age, size, growth rates and species, a tree sequesters an average of 21.77 kg of CO2 per year).  And the rate of the absorption will remain positive, as long as incremental tree growth exceeds decomposition.  Therefore, forests act as carbon sinks that give off oxygen as a by-product at a relatively low cost. Not only that, but they provide habitats for wildlife, conservation of biodiversity, watershed protection, soil erosion control, and a host of many other socio-economic benefits.
If serious steps are not taken to mitigate global warming and the greenhouse gas emissions, air pollution will not be the only detrimental effect. But things like, extinction of animal and plant species, disruption of agriculture and a global economic crisis could arise. 
CO2 offsetting example: weekend trip in Barcelona
let’s go back to the earlier hypothetical 3-day holiday trip to Barcelona and put the numbers into the equation.
For a 3-day trip from London to Barcelona that generates around 149.78 kg CO2, it would take one year for around 8 trees to offset all the emissions caused by the vacation, and after that any carbon sequestered by these planted trees will only be a bonus.
Lead researcher from the University of Sydney, Professor Manfred Lenzen, recommends that vacationers take steps in mitigating or offsetting the pollution caused by their travels. “To make my own travel more sustainable – for future generations – I invest in long-run abatement options at prices that incorporate at least average abatement costs, like investing in afforestation, rather than assuming only low-hanging fruit, like residential power efficiency,” - He told The Independent.
Offset your travels' CO2 emissions
Now organizations that encourage carbon neutral living have online calculators that can calculate people’s monthly or annual carbon footprint, by analysing the impact of things like their lifestyle, diet or travel trips have on the atmosphere.
The commitment of organisations like Rosian.org to funding sustainable afforestation and reforestation projects offer a brilliant way of helping this vital environmental cause and saving the green planet.
You can help today save the planet by making small green conscious decisions concerning your travel!
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