I have a global land cover map, which has the following properties: Name ESACCI-LC-L4-LCCS-Map-300m-P5Y-2010-v1.6.1 Path C:\QGIS\ESACCI-LC-L4-LCCS-Map-300m-P5Y-2010-v1.6.1.tif\ESACCI-LC-L4-LCCS-Map-300m-P5Y-2010-v1.6.1.tif
CRS EPSG:4326 - WGS 84 - Geographic
Extent -180.0000003392726740,-89.9999950369175963 : 179.9999897345625186,90.0000000000000000
Unit degrees
Width 129600
Height 64800
Data type Byte - Eight bit unsigned integer
GDAL Driver Description GTiff
GDAL Driver Metadata GeoTIFF
Dataset Description C:\QGIS\ESACCI-LC-L4-LCCS-Map-300m-P5Y-2010-v1.6.1.tif\ESACCI-LC-L4-LCCS-Map-300m-P5Y-2010-v1.6.1.tif
Compression LZW
Band 1 • STATISTICS_APPROXIMATE=YES
• STATISTICS_MAXIMUM=220
• STATISTICS_MEAN=188.20256246321
• STATISTICS_MINIMUM=10
• STATISTICS_STDDEV=53.693285876722
• STATISTICS_VALID_PERCENT=100
More information • AREA_OR_POINT=Area
• Authors=Pierre Defourny ,Eric Van Bogaert
• Copyright=Copyright ©UCL Geomatics, BELGIUM 1999-2012
• Generate by=gdal_ocl
• process begin time=2015-08-24T20:26:40
• process finish time=2015-08-24T20:51:20
Dimensions X: 129600 Y: 64800 Bands: 1
Origin -180,90
Pixel Size 0.002777777701186999893,-0.002777777701186999893
To clip continents I used shp file of countries, which has following properties: Fixed geometries Source
MultiPolygon?crs=EPSG:4326&field=OBJECTID:double(19,0)&field=COUNTRY_NA:string(254,0)&field=Shape_Leng:double(32,15)&field=Shape_Le_1:double(32,15)&field=Shape_Area:double(32,15)&uid={afd52bdd-db05-480d-acf5-932252071748}
Storage Memory storage Comment
Encoding
UTF-8
Geometry
Polygon (MultiPolygon)
CRS
EPSG:4326 - WGS 84 - Geographic
Extent
-179.9999999999999716,-89.9999999999999432 : 180.0000000000000000,83.6333923340000638
Unit: degrees
Feature count: 279
I collected African countries to be used as mask. Africa was clipped and the new layer has the following properties:
Path C:\Users\User\AppData\Local\Temp\processing_049cf2b8a5b041639ace295d17d3d405\1c8919fd7e01488e8d7dacc10cd06c93\OUTPUT.tif
CRS
EPSG:4326 - WGS 84 - Geographic
Extent
-25.3611104118373092,-46.9805542601757296 : 73.7444424111124590,37.5444434092434918
Unit
degrees
Width
35678
Height
30429
Data type
Byte - Eight bit unsigned integer
GDAL Driver Description
GTiff
GDAL Driver Metadata
GeoTIFF
Dataset Description
C:/Users/User/AppData/Local/Temp/processing_049cf2b8a5b041639ace295d17d3d405/1c8919fd7e01488e8d7dacc10cd06c93/OUTPUT.tif
Compression
Band 1
STATISTICS_APPROXIMATE=YES
STATISTICS_MAXIMUM=220
STATISTICS_MEAN=115.01767969776
STATISTICS_MINIMUM=10
STATISTICS_STDDEV=74.622799277297
STATISTICS_VALID_PERCENT=30.52
Band 2
More information
AREA_OR_POINT=Area
Authors=Pierre Defourny ,Eric Van Bogaert
Copyright=Copyright ©UCL Geomatics, BELGIUM 1999-2012
Generate by=gdal_ocl
process begin time=2015-08-24T20:26:40
process finish time=2015-08-24T20:51:20
Dimensions
X: 35678 Y: 30429 Bands: 2
Origin
-25.3611,37.5444
Pixel Size
0.002777777701186999893,-0.002777777701186999893
To measure area I used r.report plugin. The result is the following: 
I reprojected the clipped layer to 102022 and r.report plugin was running again. The result is the following: 
What mistakes have I make?
