The top 20 skyscrapers in 2020

1. Kingdom Tower, Jeddah, Saudi Arabia  (1000m or 1007m) (proposed)
2. Burj Khalifa, Dubai (828m) (completed 2010)
3. Ping An Finance Center, Shenzhen (660m) (under construction)
4. Seoul Light DMC Tower (640m) (cancelled)
5. Signature Tower, Jakarta (638m) (proposed)
6. Shanghai Tower (632m) (under construction)
7. Wuhan Greenland Center (606m or 636m) (proposed)
8. Makkah Royal Clock Tower (601m) (completed 2012)
9. Goldin Finance 117, Tianjin (597m) (under construction)
10. Lotte World Tower, Seoul (556m) (under construction)
11. Doha Convention Center Tower (551m) (construction stopped)
12. One World Trade Center, New York (541m) (topped out)
13. The CTF Guangzhou (East Tower) (530m) (under construction)
14. Tianjin CTF Binhai Center (530m) (under construction)
15. Dalian Greenland Center (518m) (under construction)
16. Pentominium Dubai (516m) (construction stopped)
17. Busan Lotte Town Tower (510m) (under construction)
18. Taipei 101 (508m) (completed 2004)
19. Kaisa Feng Long Center Shenzhen (500m or 518m) (proposed)
20. Shanghai World Finance Center (492m ) (completed 2008)
21. International Commerce Centre, Hong Kong (484m) (completed 2010)
22. Petronas Towers, Kuala Lumpur (452m) (completed 1998)

Source: http://ctbuh.org/TallBuildings/HeightStatistics/BuildingsinNumbers/TheTallest20in2020/tabid/2926/language/en-US/Default.aspx

Additional proposed buildings:
Nakheel Harbour and Tower, Dubai (1400m) (abandoned)
Azerbaijan Tower, Baku (1050m) (proposed)
Lagoons Tower, Dubai (1000+m) (proposed)
Miapolis, Miami (975m) (proposed)
Sky City, Changsha (847m or 838m or 666m) (proposed)
Suzhou Center Plaza, Suzhou, China, (780m) (proposed)
Wuhan Riverfront Erqi Project (707m) (proposed)
777 Tower, Qingdao (700m) (proposed)
India Tower, Mumbai (700m or 720m) (construction stopped)
Zhuhai Shizimen CBD Tower (680m) (proposed)
Caiwuwei Financial Center, Shenzhen (666m) (proposed)
Park Square Tower, Dubai (666m) (proposed)
Wuhan Hanzheng Jie (666m) (proposed)
Dream Tower, Yongsan, Seoul (665m) (proposed)
Pagcor Tower, Manila (665m) (proposed)
Wuhan Wangjiadun (660m) (conceptual)
Bangalore Turf Tower (660m) (approved)
City Tower, Sao Paulo (650m) (proposed)
Guangzhou Baietan Diamond Tower (650m) (conceptual) 
Tower of Russia, Moscow (648m) (proposed)
Financial Street Concord City Tower, Chongqing (639m) (proposed)
Wuhan Hua's Tower (638m) (proposed)
Jinan Tower (638m) (proposed)
Tianlong Fortune Center, Nanning (628m) (proposed)
Triple One, Seoul (620m) (proposed)
Nanping Twin Towers, Chongqing (620m) (proposed)
Xiamen Harmony 888 (620m) (proposed)
Russia Tower (612m) (construction stopped)
Chicago Spire (610m) (construction stopped; abandoned)
BUMN Tower, Jakarta (610m) (proposed)
Lanco Hills Signature Tower, Hyderabad (604m or 630m) (under construction proposed)
Incheon (South Korea), 151 Tower (601m) (proposed)
Guangzhou International Financial City (600m) (proposed)
Port Tower Complex, Karachi (593m) (proposed)
Rose Rock Center, Tianjin (588m) (proposed)
Evergrande IFC, Jinan, China, 560m (proposed)
The Diamond, Phnom Penh (555m) (proposed)
Shanghai World Financial Center (550m) (proposed)
Hyundai Global Business Center, Seoul (540m) (proposed)
Jiangyin Dragon Tower (538m) (conceptual)
Menara Warisan Merdeka, Kuala Lumpur (525m or 600m) (proposed)
China Resources Headquarters; Shenzen, China (525 m) (proposed)
Shenzhen KFL Center (518m or 500m) (proposed)
Zhongguo (China) Zun, Beijing (510m, 520m, 528m or 536m) (under construction)
Burj Al Alam, Dubai (510m) (construction stopped)
Qatar National Bank Tower (510m) (construction stopped)
Federation Tower, Moscow (506m) (under construction) (only 360m)
Dalian International Trade Center (500m) (proposed)
Beijing Citic Plaza (500m) (approved)
Tianjin Yujiabao (500m) (approved)
Wuhan International Business Center (500m) (conceptual)
Chongqing Danzishi (500m) (conceptual)
Al Quds Tower, Doha (500m) (on hold)
Suzhou Century Plaza (500m or 700m) (proposed) 
Lakta Center, St. Petersburg (473m) (proposed)

Source: http://www.businessinsider.com/tallest-proposed-buildings-in-the-world-2012-5?op=1 and
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